21621672225 has 144 divisors (see below), whose sum is σ = 41072496192. Its totient is φ = 11273333760.

The previous prime is 21621672217. The next prime is 21621672229. The reversal of 21621672225 is 52227612612.

21621672225 is a `hidden beast` number, since 2 + 1 + 621 + 6 + 7 + 2 + 2 + 25 = 666.

It is not a de Polignac number, because 21621672225 - 2³ = 21621672217 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21621672225.

It is not an unprimeable number, because it can be changed into a prime (21621672229) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 69078669 + ... + 69078981.

It is an arithmetic number, because the mean of its divisors is an integer number (285225668).

Almost surely, 2^21621672225 is an apocalyptic number.

21621672225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21621672225 is a deficient number, since it is larger than the sum of its proper divisors (19450823967).

21621672225 is a wasteful number, since it uses less digits than its factorization.

21621672225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 558 (or 541 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The spelling of 21621672225 in words is "twenty-one billion, six hundred twenty-one million, six hundred seventy-two thousand, two hundred twenty-five".