21298725 has 36 divisors (see below), whose sum is σ = 43601376. Its totient is φ = 9735840.

The previous prime is 21298723. The next prime is 21298741. The reversal of 21298725 is 52789212.

It is not a de Polignac number, because 21298725 - 2¹ = 21298723 is a prime.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21298725.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21298723) by changing a digit.

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 35 ways as a sum of consecutive naturals, for example, 5187 + ... + 8336.

Almost surely, 2^21298725 is an apocalyptic number.

21298725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21298725 is an abundant number, since it is smaller than the sum of its proper divisors (22302651).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21298725 is a wasteful number, since it uses less digits than its factorization.

21298725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13546 (or 13538 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 21298725 is about 4615.0541708630. The cubic root of 21298725 is about 277.1944530789.

The spelling of 21298725 in words is "twenty-one million, two hundred ninety-eight thousand, seven hundred twenty-five".