21561616522 has 16 divisors (see below), whose sum is σ = 33477949440. Its totient is φ = 10402750512.

The previous prime is 21561616507. The next prime is 21561616523. The reversal of 21561616522 is 22561616512.

It is not an unprimeable number, because it can be changed into a prime (21561616523) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15318 + ... + 208225.

It is an arithmetic number, because the mean of its divisors is an integer number (2092371840).

Almost surely, 2^21561616522 is an apocalyptic number.

21561616522 is a deficient number, since it is larger than the sum of its proper divisors (11916332918).

21561616522 is a wasteful number, since it uses less digits than its factorization.

21561616522 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 225237.

The product of its digits is 43200, while the sum is 37.

The spelling of 21561616522 in words is "twenty-one billion, five hundred sixty-one million, six hundred sixteen thousand, five hundred twenty-two".