21775144 has 16 divisors (see below), whose sum is σ = 42145920. Its totient is φ = 10536240.

The previous prime is 21775139. The next prime is 21775183. The reversal of 21775144 is 44157712.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43654 + ... + 44149.

It is an arithmetic number, because the mean of its divisors is an integer number (2634120).

Almost surely, 2^21775144 is an apocalyptic number.

It is an amenable number.

21775144 is a deficient number, since it is larger than the sum of its proper divisors (20370776).

21775144 is a wasteful number, since it uses less digits than its factorization.

21775144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87840 (or 87836 counting only the distinct ones).

The product of its digits is 7840, while the sum is 31.

The square root of 21775144 is about 4666.3844676580. The cubic root of 21775144 is about 279.2460328092.

The spelling of 21775144 in words is "twenty-one million, seven hundred seventy-five thousand, one hundred forty-four".