21255144 has 32 divisors (see below), whose sum is σ = 54972000. Its totient is φ = 6840512.

The previous prime is 21255133. The next prime is 21255161. The reversal of 21255144 is 44155212.

It is a super-2 number, since 2×21255144² = 903562292921472, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (24).

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, 14574 + ... + 15965.

It is an arithmetic number, because the mean of its divisors is an integer number (1717875).

Almost surely, 2^21255144 is an apocalyptic number.

21255144 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21255144 is an abundant number, since it is smaller than the sum of its proper divisors (33716856).

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

21255144 is a wasteful number, since it uses less digits than its factorization.

21255144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30577 (or 30573 counting only the distinct ones).

The product of its digits is 1600, while the sum is 24.

The square root of 21255144 is about 4610.3301400225. The cubic root of 21255144 is about 277.0052608401.

The spelling of 21255144 in words is "twenty-one million, two hundred fifty-five thousand, one hundred forty-four".