21615377556156 has 144 divisors (see below), whose sum is σ = 55141950864000. Its totient is φ = 6571628146944.

The previous prime is 21615377556131. The next prime is 21615377556187. The reversal of 21615377556156 is 65165577351612.

It is a self number, because there is not a number n which added to its sum of digits gives 21615377556156.

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 47 ways as a sum of consecutive naturals, for example, 66758551 + ... + 67081553.

Almost surely, 2^{21615377556156} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21615377556156, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27570975432000).

21615377556156 is an abundant number, since it is smaller than the sum of its proper divisors (33526573307844).

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

21615377556156 is a wasteful number, since it uses less digits than its factorization.

21615377556156 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 323436 (or 323405 counting only the distinct ones).

The product of its digits is 39690000, while the sum is 60.

The spelling of 21615377556156 in words is "twenty-one trillion, six hundred fifteen billion, three hundred seventy-seven million, five hundred fifty-six thousand, one hundred fifty-six".