21491747260 has 24 divisors (see below), whose sum is σ = 45135966960. Its totient is φ = 8596070784.

The previous prime is 21491747243. The next prime is 21491747279. The reversal of 21491747260 is 6274719412.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 322711 + ... + 383569.

It is an arithmetic number, because the mean of its divisors is an integer number (1880665290).

Almost surely, 2^21491747260 is an apocalyptic number.

21491747260 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21491747260 is an abundant number, since it is smaller than the sum of its proper divisors (23644219700).

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

21491747260 is a wasteful number, since it uses less digits than its factorization.

21491747260 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78525 (or 78523 counting only the distinct ones).

The product of its (nonzero) digits is 169344, while the sum is 43.

The spelling of 21491747260 in words is "twenty-one billion, four hundred ninety-one million, seven hundred forty-seven thousand, two hundred sixty".