21018387264 has 112 divisors (see below), whose sum is σ = 63923680128. Its totient is φ = 5970475008.

The previous prime is 21018387259. The next prime is 21018387281. The reversal of 21018387264 is 46278381012.

It is a tau number, because it is divible by the number of its divisors (112).

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 187314 + ... + 277710.

It is an arithmetic number, because the mean of its divisors is an integer number (570747144).

Almost surely, 2^21018387264 is an apocalyptic number.

21018387264 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 21018387264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31961840064).

21018387264 is an abundant number, since it is smaller than the sum of its proper divisors (42905292864).

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

21018387264 is a wasteful number, since it uses less digits than its factorization.

21018387264 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90592 (or 90582 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 42.

The spelling of 21018387264 in words is "twenty-one billion, eighteen million, three hundred eighty-seven thousand, two hundred sixty-four".