21290525 has 24 divisors (see below), whose sum is σ = 28045824. Its totient is φ = 15998400.

The previous prime is 21290519. The next prime is 21290531. The reversal of 21290525 is 52509212.

It is an interprime number because it is at equal distance from previous prime (21290519) and next prime (21290531).

It is not a de Polignac number, because 21290525 - 2⁴ = 21290509 is a prime.

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

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21290494 and 21290503.

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 23 ways as a sum of consecutive naturals, for example, 34772 + ... + 35378.

It is an arithmetic number, because the mean of its divisors is an integer number (1168576).

Almost surely, 2^21290525 is an apocalyptic number.

21290525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21290525 is a deficient number, since it is larger than the sum of its proper divisors (6755299).

21290525 is a wasteful number, since it uses less digits than its factorization.

21290525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 701 (or 696 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 21290525 is about 4614.1656883991. The cubic root of 21290525 is about 277.1588752641.

Adding to 21290525 its reverse (52509212), we get a palindrome (73799737).

The spelling of 21290525 in words is "twenty-one million, two hundred ninety thousand, five hundred twenty-five".