21040187784 has 64 divisors (see below), whose sum is σ = 65579811840. Its totient is φ = 5464983360.

The previous prime is 21040187767. The next prime is 21040187843. The reversal of 21040187784 is 48778104012.

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

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, 5690844 + ... + 5694539.

It is an arithmetic number, because the mean of its divisors is an integer number (1024684560).

Almost surely, 2^21040187784 is an apocalyptic number.

21040187784 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21040187784 is an abundant number, since it is smaller than the sum of its proper divisors (44539624056).

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

21040187784 is a wasteful number, since it uses less digits than its factorization.

21040187784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11385410 (or 11385406 counting only the distinct ones).

The product of its (nonzero) digits is 100352, while the sum is 42.

The spelling of 21040187784 in words is "twenty-one billion, forty million, one hundred eighty-seven thousand, seven hundred eighty-four".