21695725 has 6 divisors (see below), whose sum is σ = 26902730. Its totient is φ = 17356560.

The previous prime is 21695669. The next prime is 21695747. The reversal of 21695725 is 52759612.

It can be written as a sum of positive squares in 3 ways, for example, as 636804 + 21058921 = 798^2 + 4589^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21695725 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 433890 + ... + 433939.

Almost surely, 2^21695725 is an apocalyptic number.

21695725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21695725 is a deficient number, since it is larger than the sum of its proper divisors (5207005).

21695725 is an equidigital number, since it uses as much as digits as its factorization.

21695725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 867839 (or 867834 counting only the distinct ones).

The product of its digits is 37800, while the sum is 37.

The square root of 21695725 is about 4657.8670011068. The cubic root of 21695725 is about 278.9061275555.

The spelling of 21695725 in words is "twenty-one million, six hundred ninety-five thousand, seven hundred twenty-five".