21987325 has 6 divisors (see below), whose sum is σ = 27264314. Its totient is φ = 17589840.

The previous prime is 21987299. The next prime is 21987331. The reversal of 21987325 is 52378912.

It can be written as a sum of positive squares in 3 ways, for example, as 4897369 + 17089956 = 2213^2 + 4134^2 .

It is not a de Polignac number, because 21987325 - 2⁵ = 21987293 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 439722 + ... + 439771.

Almost surely, 2^21987325 is an apocalyptic number.

21987325 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21987325 is a deficient number, since it is larger than the sum of its proper divisors (5276989).

21987325 is an equidigital number, since it uses as much as digits as its factorization.

21987325 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 879503 (or 879498 counting only the distinct ones).

The product of its digits is 30240, while the sum is 37.

The square root of 21987325 is about 4689.0644056144. The cubic root of 21987325 is about 280.1501108362.

The spelling of 21987325 in words is "twenty-one million, nine hundred eighty-seven thousand, three hundred twenty-five".