21519625 has 8 divisors (see below), whose sum is σ = 26856648. Its totient is φ = 17215600.

The previous prime is 21519599. The next prime is 21519677. The reversal of 21519625 is 52691512.

It can be written as a sum of positive squares in 4 ways, for example, as 3337929 + 18181696 = 1827^2 + 4264^2 .

It is not a de Polignac number, because 21519625 - 2⁷ = 21519497 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 85954 + ... + 86203.

It is an arithmetic number, because the mean of its divisors is an integer number (3357081).

Almost surely, 2^21519625 is an apocalyptic number.

21519625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21519625 is a deficient number, since it is larger than the sum of its proper divisors (5337023).

21519625 is an equidigital number, since it uses as much as digits as its factorization.

21519625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172172 (or 172162 counting only the distinct ones).

The product of its digits is 5400, while the sum is 31.

The square root of 21519625 is about 4638.9249832262. The cubic root of 21519625 is about 278.1494676114.

The spelling of 21519625 in words is "twenty-one million, five hundred nineteen thousand, six hundred twenty-five".