21387125 has 32 divisors (see below), whose sum is σ = 28664064. Its totient is φ = 15892800.

The previous prime is 21387109. The next prime is 21387151. The reversal of 21387125 is 52178312.

It is not a de Polignac number, because 21387125 - 2⁴ = 21387109 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 123539 + ... + 123711.

It is an arithmetic number, because the mean of its divisors is an integer number (895752).

Almost surely, 2^21387125 is an apocalyptic number.

21387125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21387125 is a deficient number, since it is larger than the sum of its proper divisors (7276939).

21387125 is a wasteful number, since it uses less digits than its factorization.

21387125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 254 (or 244 counting only the distinct ones).

The product of its digits is 3360, while the sum is 29.

The square root of 21387125 is about 4624.6216061425. The cubic root of 21387125 is about 277.5774207053.

It can be divided in two parts, 21387 and 125, that added together give a palindrome (21512).

The spelling of 21387125 in words is "twenty-one million, three hundred eighty-seven thousand, one hundred twenty-five".