21317625 has 48 divisors (see below), whose sum is σ = 43934592. Its totient is φ = 9741600.

The previous prime is 21317623. The next prime is 21317627. The reversal of 21317625 is 52671312.

It is a happy number.

21317625 is a `hidden beast` number, since 2 + 1 + 31 + 7 + 625 = 666.

It is an interprime number because it is at equal distance from previous prime (21317623) and next prime (21317627).

It is not a de Polignac number, because 21317625 - 2¹ = 21317623 is a prime.

It is a super-2 number, since 2×21317625² = 908882271281250, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21317623) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 6522 + ... + 9228.

It is an arithmetic number, because the mean of its divisors is an integer number (915304).

Almost surely, 2^21317625 is an apocalyptic number.

21317625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21317625 is an abundant number, since it is smaller than the sum of its proper divisors (22616967).

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

21317625 is a wasteful number, since it uses less digits than its factorization.

21317625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2735 (or 2722 counting only the distinct ones).

The product of its digits is 2520, while the sum is 27.

The square root of 21317625 is about 4617.1013634097. The cubic root of 21317625 is about 277.2764208380.

Adding to 21317625 its reverse (52671312), we get a palindrome (73988937).

The spelling of 21317625 in words is "twenty-one million, three hundred seventeen thousand, six hundred twenty-five".