21053725 has 24 divisors (see below), whose sum is σ = 32551488. Its totient is φ = 13123200.

The previous prime is 21053713. The next prime is 21053731. The reversal of 21053725 is 52735012.

It is not a de Polignac number, because 21053725 - 2⁷ = 21053597 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21053725.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3544 + ... + 7393.

It is an arithmetic number, because the mean of its divisors is an integer number (1356312).

Almost surely, 2^21053725 is an apocalyptic number.

21053725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21053725 is a deficient number, since it is larger than the sum of its proper divisors (11497763).

21053725 is a wasteful number, since it uses less digits than its factorization.

21053725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10965 (or 10960 counting only the distinct ones).

The product of its (nonzero) digits is 2100, while the sum is 25.

The square root of 21053725 is about 4588.4338286609. The cubic root of 21053725 is about 276.1274922084.

Adding to 21053725 its reverse (52735012), we get a palindrome (73788737).

It can be divided in two parts, 210 and 53725, that added together give a palindrome (53935).

The spelling of 21053725 in words is "twenty-one million, fifty-three thousand, seven hundred twenty-five".