21105477880 has 32 divisors (see below), whose sum is σ = 47584085040. Its totient is φ = 8424989440.

The previous prime is 21105477859. The next prime is 21105477893. The reversal of 21105477880 is 8877450112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 517669 + ... + 556948.

Almost surely, 2^21105477880 is an apocalyptic number.

21105477880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21105477880 is an abundant number, since it is smaller than the sum of its proper divisors (26478607160).

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

21105477880 is a wasteful number, since it uses less digits than its factorization.

21105477880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1075119 (or 1075115 counting only the distinct ones).

The product of its (nonzero) digits is 125440, while the sum is 43.

The spelling of 21105477880 in words is "twenty-one billion, one hundred five million, four hundred seventy-seven thousand, eight hundred eighty".