21437725 has 18 divisors (see below), whose sum is σ = 27805946. Its totient is φ = 16394400.

The previous prime is 21437723. The next prime is 21437747. The reversal of 21437725 is 52773412.

It can be written as a sum of positive squares in 3 ways, for example, as 3136441 + 18301284 = 1771^2 + 4278^2 .

It is not a de Polignac number, because 21437725 - 2¹ = 21437723 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21437723) 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 17 ways as a sum of consecutive naturals, for example, 12415 + ... + 14035.

Almost surely, 2^21437725 is an apocalyptic number.

21437725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21437725 is a deficient number, since it is larger than the sum of its proper divisors (6368221).

21437725 is a wasteful number, since it uses less digits than its factorization.

21437725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1677 (or 1649 counting only the distinct ones).

The product of its digits is 11760, while the sum is 31.

The square root of 21437725 is about 4630.0890920154. The cubic root of 21437725 is about 277.7961559692.

The spelling of 21437725 in words is "twenty-one million, four hundred thirty-seven thousand, seven hundred twenty-five".