21155760 has 60 divisors (see below), whose sum is σ = 71050512. Its totient is φ = 5641344.

The previous prime is 21155753. The next prime is 21155773. The reversal of 21155760 is 6755112.

It is a tau number, because it is divible by the number of its divisors (60).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13972 + ... + 15411.

Almost surely, 2^21155760 is an apocalyptic number.

21155760 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21155760 is an abundant number, since it is smaller than the sum of its proper divisors (49894752).

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

21155760 is a wasteful number, since it uses less digits than its factorization.

21155760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29402 (or 29393 counting only the distinct ones).

The product of its (nonzero) digits is 2100, while the sum is 27.

The square root of 21155760 is about 4599.5391073454. The cubic root of 21155760 is about 276.5728492728.

It can be divided in two parts, 2115 and 5760, that added together give a triangular number (7875 = T₁₂₅).

The spelling of 21155760 in words is "twenty-one million, one hundred fifty-five thousand, seven hundred sixty".