21387703568 has 80 divisors (see below), whose sum is σ = 51760913280. Its totient is φ = 8317209600.

The previous prime is 21387703567. The next prime is 21387703577. The reversal of 21387703568 is 86530778312.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21387703567) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 650468 + ... + 682556.

It is an arithmetic number, because the mean of its divisors is an integer number (647011416).

Almost surely, 2^21387703568 is an apocalyptic number.

21387703568 is a gapful number since it is divisible by the number (28) 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 21387703568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25880456640).

21387703568 is an abundant number, since it is smaller than the sum of its proper divisors (30373209712).

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

21387703568 is a wasteful number, since it uses less digits than its factorization.

21387703568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32656 (or 32650 counting only the distinct ones).

The product of its (nonzero) digits is 1693440, while the sum is 50.

The spelling of 21387703568 in words is "twenty-one billion, three hundred eighty-seven million, seven hundred three thousand, five hundred sixty-eight".