21311625 has 32 divisors (see below), whose sum is σ = 37559808. Its totient is φ = 10694400.

The previous prime is 21311623. The next prime is 21311629. The reversal of 21311625 is 52611312.

It is not a de Polignac number, because 21311625 - 2¹ = 21311623 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21311621) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4704 + ... + 8046.

It is an arithmetic number, because the mean of its divisors is an integer number (1173744).

Almost surely, 2^21311625 is an apocalyptic number.

21311625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21311625 is a deficient number, since it is larger than the sum of its proper divisors (16248183).

21311625 is a wasteful number, since it uses less digits than its factorization.

21311625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3378 (or 3368 counting only the distinct ones).

The product of its digits is 360, while the sum is 21.

The square root of 21311625 is about 4616.4515593689. The cubic root of 21311625 is about 277.2504045778.

Adding to 21311625 its reverse (52611312), we get a palindrome (73922937).

The spelling of 21311625 in words is "twenty-one million, three hundred eleven thousand, six hundred twenty-five".