21331760 has 20 divisors (see below), whose sum is σ = 49596528. Its totient is φ = 8532672.

The previous prime is 21331729. The next prime is 21331777. The reversal of 21331760 is 6713312.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (20).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 133244 + ... + 133403.

Almost surely, 2^21331760 is an apocalyptic number.

21331760 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21331760 is an abundant number, since it is smaller than the sum of its proper divisors (28264768).

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

21331760 is a wasteful number, since it uses less digits than its factorization.

21331760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 266660 (or 266654 counting only the distinct ones).

The product of its (nonzero) digits is 756, while the sum is 23.

The square root of 21331760 is about 4618.6318320472. The cubic root of 21331760 is about 277.3376915201.

The spelling of 21331760 in words is "twenty-one million, three hundred thirty-one thousand, seven hundred sixty".