21551541264 has 160 divisors (see below), whose sum is σ = 67548593280. Its totient is φ = 6524582400.

The previous prime is 21551541251. The next prime is 21551541287. The reversal of 21551541264 is 46214515512.

21551541264 is a `hidden beast` number, since 2 + 1 + 5 + 51 + 541 + 2 + 64 = 666.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 8842254 + ... + 8844690.

It is an arithmetic number, because the mean of its divisors is an integer number (422178708).

Almost surely, 2^21551541264 is an apocalyptic number.

21551541264 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21551541264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33774296640).

21551541264 is an abundant number, since it is smaller than the sum of its proper divisors (45997052016).

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

21551541264 is a wasteful number, since it uses less digits than its factorization.

21551541264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4326 (or 4314 counting only the distinct ones).

The product of its digits is 48000, while the sum is 36.

The spelling of 21551541264 in words is "twenty-one billion, five hundred fifty-one million, five hundred forty-one thousand, two hundred sixty-four".