21224521656261 has 36 divisors (see below), whose sum is σ = 38905060113504. Its totient is φ = 11025725533200.

The previous prime is 21224521656199. The next prime is 21224521656311. The reversal of 21224521656261 is 16265612542212.

21224521656261 is a `hidden beast` number, since 2 + 1 + 2 + 2 + 4 + 5 + 2 + 16 + 5 + 626 + 1 = 666.

It is not a de Polignac number, because 21224521656261 - 2¹⁰ = 21224521655237 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21224521656061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 2187639105 + ... + 2187648806.

It is an arithmetic number, because the mean of its divisors is an integer number (1080696114264).

Almost surely, 2^{21224521656261} is an apocalyptic number.

21224521656261 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21224521656261 is a deficient number, since it is larger than the sum of its proper divisors (17680538457243).

21224521656261 is a wasteful number, since it uses less digits than its factorization.

21224521656261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4375287942 (or 4375287932 counting only the distinct ones).

The product of its digits is 691200, while the sum is 45.

The spelling of 21224521656261 in words is "twenty-one trillion, two hundred twenty-four billion, five hundred twenty-one million, six hundred fifty-six thousand, two hundred sixty-one".