21247425 has 18 divisors (see below), whose sum is σ = 38056902. Its totient is φ = 11331840.

The previous prime is 21247411. The next prime is 21247439. The reversal of 21247425 is 52474212.

It is an interprime number because it is at equal distance from previous prime (21247411) and next prime (21247439).

It can be written as a sum of positive squares in 3 ways, for example, as 535824 + 20711601 = 732^2 + 4551^2 .

It is not a de Polignac number, because 21247425 - 2⁵ = 21247393 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 46992 + ... + 47441.

Almost surely, 2^21247425 is an apocalyptic number.

21247425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21247425 is a deficient number, since it is larger than the sum of its proper divisors (16809477).

21247425 is a wasteful number, since it uses less digits than its factorization.

21247425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94449 (or 94441 counting only the distinct ones).

The product of its digits is 4480, while the sum is 27.

The square root of 21247425 is about 4609.4929222204. The cubic root of 21247425 is about 276.9717244485.

The spelling of 21247425 in words is "twenty-one million, two hundred forty-seven thousand, four hundred twenty-five".