21387703566 has 16 divisors (see below), whose sum is σ = 42779826000. Its totient is φ = 7128498048.

The previous prime is 21387703559. The next prime is 21387703567. The reversal of 21387703566 is 66530778312.

It is a congruent 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 7 ways as a sum of consecutive naturals, for example, 119451 + ... + 238838.

It is an arithmetic number, because the mean of its divisors is an integer number (2673739125).

Almost surely, 2^21387703566 is an apocalyptic number.

21387703566 is an abundant number, since it is smaller than the sum of its proper divisors (21392122434).

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

21387703566 is a wasteful number, since it uses less digits than its factorization.

21387703566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 368243.

The product of its (nonzero) digits is 1270080, while the sum is 48.

The spelling of 21387703566 in words is "twenty-one billion, three hundred eighty-seven million, seven hundred three thousand, five hundred sixty-six".