21612640166520 has 128 divisors (see below), whose sum is σ = 72861342220800. Its totient is φ = 5088728646144.

The previous prime is 21612640166519. The next prime is 21612640166527. The reversal of 21612640166520 is 2566104621612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21612640166527) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 301143610 + ... + 301215369.

It is an arithmetic number, because the mean of its divisors is an integer number (569229236100).

Almost surely, 2^{21612640166520} is an apocalyptic number.

21612640166520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21612640166520 is an abundant number, since it is smaller than the sum of its proper divisors (51248702054280).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21612640166520 is a wasteful number, since it uses less digits than its factorization.

21612640166520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 602359029 (or 602359025 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 42.

The spelling of 21612640166520 in words is "twenty-one trillion, six hundred twelve billion, six hundred forty million, one hundred sixty-six thousand, five hundred twenty".