21971625 has 32 divisors (see below), whose sum is σ = 39381888. Its totient is φ = 10814400.

The previous prime is 21971623. The next prime is 21971629. The reversal of 21971625 is 52617912.

It is not a de Polignac number, because 21971625 - 2¹ = 21971623 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21971623) 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, 2622 + ... + 7128.

It is an arithmetic number, because the mean of its divisors is an integer number (1230684).

Almost surely, 2^21971625 is an apocalyptic number.

21971625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21971625 is a deficient number, since it is larger than the sum of its proper divisors (17410263).

21971625 is a wasteful number, since it uses less digits than its factorization.

21971625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4538 (or 4528 counting only the distinct ones).

The product of its digits is 7560, while the sum is 33.

The square root of 21971625 is about 4687.3899987093. The cubic root of 21971625 is about 280.0834147733.

The spelling of 21971625 in words is "twenty-one million, nine hundred seventy-one thousand, six hundred twenty-five".