21056525 has 18 divisors (see below), whose sum is σ = 30374730. Its totient is φ = 14437920.

The previous prime is 21056507. The next prime is 21056527. The reversal of 21056525 is 52565012.

It can be written as a sum of positive squares in 3 ways, for example, as 5080516 + 15976009 = 2254^2 + 3997^2 .

It is not a de Polignac number, because 21056525 - 2¹⁰ = 21055501 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a junction number, because it is equal to n+sod(n) for n = 21056494 and 21056503.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21056527) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 7370 + ... + 9819.

It is an arithmetic number, because the mean of its divisors is an integer number (1687485).

Almost surely, 2^21056525 is an apocalyptic number.

21056525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21056525 is a deficient number, since it is larger than the sum of its proper divisors (9318205).

21056525 is a wasteful number, since it uses less digits than its factorization.

21056525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17213 (or 17201 counting only the distinct ones).

The product of its (nonzero) digits is 3000, while the sum is 26.

The square root of 21056525 is about 4588.7389335198. The cubic root of 21056525 is about 276.1397326822.

The spelling of 21056525 in words is "twenty-one million, fifty-six thousand, five hundred twenty-five".