21709731665850 has 48 divisors (see below), whose sum is σ = 53864203372128. Its totient is φ = 5786673730240.

The previous prime is 21709731665849. The next prime is 21709731665861. The reversal of 21709731665850 is 5856613790712.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 32013924 + ... + 32685023.

It is an arithmetic number, because the mean of its divisors is an integer number (1122170903586).

Almost surely, 2^{21709731665850} is an apocalyptic number.

21709731665850 is an abundant number, since it is smaller than the sum of its proper divisors (32154471706278).

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

21709731665850 is a wasteful number, since it uses less digits than its factorization.

21709731665850 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64701199 (or 64701194 counting only the distinct ones).

The product of its (nonzero) digits is 19051200, while the sum is 60.

The spelling of 21709731665850 in words is "twenty-one trillion, seven hundred nine billion, seven hundred thirty-one million, six hundred sixty-five thousand, eight hundred fifty".