21272725 has 12 divisors (see below), whose sum is σ = 26714560. Its totient is φ = 16801200.

The previous prime is 21272707. The next prime is 21272731. The reversal of 21272725 is 52727212.

It is not a de Polignac number, because 21272725 - 2⁹ = 21272213 is a prime.

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

It is a junction number, because it is equal to n+sod(n) for n = 21272693 and 21272702.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3411 + ... + 7360.

Almost surely, 2^21272725 is an apocalyptic number.

21272725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21272725 is a deficient number, since it is larger than the sum of its proper divisors (5441835).

21272725 is a wasteful number, since it uses less digits than its factorization.

21272725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10860 (or 10855 counting only the distinct ones).

The product of its digits is 3920, while the sum is 28.

The square root of 21272725 is about 4612.2364423347. The cubic root of 21272725 is about 277.0816139239.

Adding to 21272725 its reverse (52727212), we get a palindrome (73999937).

The spelling of 21272725 in words is "twenty-one million, two hundred seventy-two thousand, seven hundred twenty-five".