21535620408 has 24 divisors (see below), whose sum is σ = 58325638800. Its totient is φ = 7178540112.

The previous prime is 21535620373. The next prime is 21535620439. The reversal of 21535620408 is 80402653512.

21535620408 is a `hidden beast` number, since 2 + 1 + 53 + 562 + 0 + 40 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (24).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 149552848 + ... + 149552991.

It is an arithmetic number, because the mean of its divisors is an integer number (2430234950).

Almost surely, 2^21535620408 is an apocalyptic number.

It is an amenable number.

21535620408 is an abundant number, since it is smaller than the sum of its proper divisors (36790018392).

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

21535620408 is a wasteful number, since it uses less digits than its factorization.

21535620408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 299105851 (or 299105844 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 36.

The spelling of 21535620408 in words is "twenty-one billion, five hundred thirty-five million, six hundred twenty thousand, four hundred eight".