21520551701670 has 64 divisors (see below), whose sum is σ = 59141096372736. Its totient is φ = 4909541794560.

The previous prime is 21520551701669. The next prime is 21520551701699. The reversal of 21520551701670 is 7610715502512.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 98238784 + ... + 98457603.

It is an arithmetic number, because the mean of its divisors is an integer number (924079630824).

Almost surely, 2^{21520551701670} is an apocalyptic number.

21520551701670 is an abundant number, since it is smaller than the sum of its proper divisors (37620544671066).

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

21520551701670 is a wasteful number, since it uses less digits than its factorization.

21520551701670 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196696925.

The product of its (nonzero) digits is 147000, while the sum is 42.

The spelling of 21520551701670 in words is "twenty-one trillion, five hundred twenty billion, five hundred fifty-one million, seven hundred one thousand, six hundred seventy".