21617725 has 24 divisors (see below), whose sum is σ = 28658880. Its totient is φ = 16128000.

The previous prime is 21617707. The next prime is 21617747. The reversal of 21617725 is 52771612.

It is not a de Polignac number, because 21617725 - 2¹¹ = 21615677 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 33405 + ... + 34045.

It is an arithmetic number, because the mean of its divisors is an integer number (1194120).

Almost surely, 2^21617725 is an apocalyptic number.

21617725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21617725 is a deficient number, since it is larger than the sum of its proper divisors (7041155).

21617725 is a wasteful number, since it uses less digits than its factorization.

21617725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 741 (or 736 counting only the distinct ones).

The product of its digits is 5880, while the sum is 31.

The square root of 21617725 is about 4649.4865307903. The cubic root of 21617725 is about 278.5714871169.

The spelling of 21617725 in words is "twenty-one million, six hundred seventeen thousand, seven hundred twenty-five".