21377525 has 12 divisors (see below), whose sum is σ = 28547652. Its totient is φ = 15786240.

The previous prime is 21377519. The next prime is 21377549. The reversal of 21377525 is 52577312.

It can be written as a sum of positive squares in 6 ways, for example, as 1387684 + 19989841 = 1178^2 + 4471^2 .

It is not a de Polignac number, because 21377525 - 2⁴ = 21377509 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21377491 and 21377500.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 32564 + ... + 33213.

It is an arithmetic number, because the mean of its divisors is an integer number (2378971).

Almost surely, 2^21377525 is an apocalyptic number.

21377525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21377525 is a deficient number, since it is larger than the sum of its proper divisors (7170127).

21377525 is a wasteful number, since it uses less digits than its factorization.

21377525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65800 (or 65795 counting only the distinct ones).

The product of its digits is 14700, while the sum is 32.

The square root of 21377525 is about 4623.5835668884. The cubic root of 21377525 is about 277.5358825985.

The spelling of 21377525 in words is "twenty-one million, three hundred seventy-seven thousand, five hundred twenty-five".