21237144 has 16 divisors (see below), whose sum is σ = 53092920. Its totient is φ = 7079040.

The previous prime is 21237143. The next prime is 21237157. The reversal of 21237144 is 44173212.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (24), and also a Moran number because the ratio is a prime number: 884881 = 21237144 / (2 + 1 + 2 + 3 + 7 + 1 + 4 + 4).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21237143) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 442417 + ... + 442464.

Almost surely, 2^21237144 is an apocalyptic number.

21237144 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21237144 is an abundant number, since it is smaller than the sum of its proper divisors (31855776).

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

21237144 is a wasteful number, since it uses less digits than its factorization.

21237144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 884890 (or 884886 counting only the distinct ones).

The product of its digits is 1344, while the sum is 24.

The square root of 21237144 is about 4608.3775886965. The cubic root of 21237144 is about 276.9270444351.

The spelling of 21237144 in words is "twenty-one million, two hundred thirty-seven thousand, one hundred forty-four".