21719390625 has 105 divisors (see below), whose sum is σ = 40867699543. Its totient is φ = 11495250000.

The previous prime is 21719390611. The next prime is 21719390629. The reversal of 21719390625 is 52609391712.

It is a happy number.

The square root of 21719390625 is 147375.

It is a perfect power (a square), and thus also a powerful number.

21719390625 is a `hidden beast` number, since 2 + 1 + 7 + 19 + 3 + 9 + 0 + 625 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 19028271249 + 2691119376 = 137943^2 + 51876^2 .

It is not a de Polignac number, because 21719390625 - 2¹⁷ = 21719259553 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21719390629) by changing a digit.

It is a polite number, since it can be written in 104 ways as a sum of consecutive naturals, for example, 165796810 + ... + 165796940.

Almost surely, 2^21719390625 is an apocalyptic number.

21719390625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21719390625 is the 147375-th square number.

21719390625 is the 73688-th centered octagonal number.

It is an amenable number.

21719390625 is a deficient number, since it is larger than the sum of its proper divisors (19148308918).

21719390625 is an frugal number, since it uses more digits than its factorization.

21719390625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 304 (or 139 counting only the distinct ones).

The product of its (nonzero) digits is 204120, while the sum is 45.

The spelling of 21719390625 in words is "twenty-one billion, seven hundred nineteen million, three hundred ninety thousand, six hundred twenty-five".