21561038634 has 16 divisors (see below), whose sum is σ = 43215219072. Its totient is φ = 7171489248.

The previous prime is 21561038621. The next prime is 21561038677. The reversal of 21561038634 is 43683016512.

It is a junction number, because it is equal to n+sod(n) for n = 21561038592 and 21561038601.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3877899 + ... + 3883454.

It is an arithmetic number, because the mean of its divisors is an integer number (2700951192).

Almost surely, 2^21561038634 is an apocalyptic number.

21561038634 is an abundant number, since it is smaller than the sum of its proper divisors (21654180438).

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

21561038634 is a wasteful number, since it uses less digits than its factorization.

21561038634 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7761821.

The product of its (nonzero) digits is 103680, while the sum is 39.

The spelling of 21561038634 in words is "twenty-one billion, five hundred sixty-one million, thirty-eight thousand, six hundred thirty-four".