221651698401 has 189 divisors, whose sum is σ = 402576041091. Its totient is φ = 121624330464.

The previous prime is 221651698399. The next prime is 221651698403. The reversal of 221651698401 is 104896156122.

The square root of 221651698401 is 470799.

It is a perfect power (a square), and thus also a powerful number.

221651698401 is a `hidden beast` number, since 2 + 2 + 1 + 6 + 516 + 98 + 40 + 1 = 666.

221651698401 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (221651698399) and next prime (221651698403).

It can be written as a sum of positive squares in only one way, i.e., 159788070225 + 61863628176 = 399735^2 + 248724^2 .

It is a tau number, because it is divible by the number of its divisors (189).

It is not a de Polignac number, because 221651698401 - 2¹ = 221651698399 is a prime.

It is not an unprimeable number, because it can be changed into a prime (221651698403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 188 ways as a sum of consecutive naturals, for example, 4182107491 + ... + 4182107543.

Almost surely, 2^221651698401 is an apocalyptic number.

221651698401 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

221651698401 is the 470799-th square number.

221651698401 is the 235400-th centered octagonal number.

It is an amenable number.

221651698401 is a deficient number, since it is larger than the sum of its proper divisors (180924342690).

221651698401 is an frugal number, since it uses more digits than its factorization.

221651698401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232 (or 110 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 45.

The spelling of 221651698401 in words is "two hundred twenty-one billion, six hundred fifty-one million, six hundred ninety-eight thousand, four hundred one".