21115564002 has 64 divisors (see below), whose sum is σ = 50636718720. Its totient is φ = 6483758400.

The previous prime is 21115563991. The next prime is 21115564009. The reversal of 21115564002 is 20046551112.

21115564002 is a `hidden beast` number, since 2 + 1 + 1 + 15 + 5 + 640 + 0 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21115564009) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 314052 + ... + 375312.

It is an arithmetic number, because the mean of its divisors is an integer number (791198730).

Almost surely, 2^21115564002 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21115564002, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25318359360).

21115564002 is an abundant number, since it is smaller than the sum of its proper divisors (29521154718).

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

21115564002 is a wasteful number, since it uses less digits than its factorization.

21115564002 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61776 (or 61770 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 27.

The spelling of 21115564002 in words is "twenty-one billion, one hundred fifteen million, five hundred sixty-four thousand, two".