1221898106025 has 27 divisors (see below), whose sum is σ = 2188584973029. Its totient is φ = 651670146720.

The previous prime is 1221898105997. The next prime is 1221898106041. The reversal of 1221898106025 is 5206018981221.

The square root of 1221898106025 is 1105395.

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

1221898106025 is a `hidden beast` number, since 1 + 2 + 21 + 8 + 9 + 8 + 10 + 602 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 104632193961 + 1117265912064 = 323469^2 + 1057008^2 .

It is not a de Polignac number, because 1221898106025 - 2²⁹ = 1221361235113 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is an unprimeable number.

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 26 ways as a sum of consecutive naturals, for example, 16544079 + ... + 16617771.

Almost surely, 2^{1221898106025} is an apocalyptic number.

1221898106025 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1221898106025 is the 1105395-th square number.

1221898106025 is the 552698-th centered octagonal number.

It is an amenable number.

1221898106025 is a deficient number, since it is larger than the sum of its proper divisors (966686867004).

1221898106025 is an frugal number, since it uses more digits than its factorization.

1221898106025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147402 (or 73701 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 45.

The spelling of 1221898106025 in words is "one trillion, two hundred twenty-one billion, eight hundred ninety-eight million, one hundred six thousand, twenty-five".