21813040825 has 12 divisors (see below), whose sum is σ = 27086342380. Its totient is φ = 17425805760.

The previous prime is 21813040811. The next prime is 21813040831. The reversal of 21813040825 is 52804031812.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 4196318841 + 17616721984 = 64779^2 + 132728^2 .

It is not a de Polignac number, because 21813040825 - 2²¹ = 21810943673 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 597594 + ... + 633043.

Almost surely, 2^21813040825 is an apocalyptic number.

21813040825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21813040825 is a deficient number, since it is larger than the sum of its proper divisors (5273301555).

21813040825 is a wasteful number, since it uses less digits than its factorization.

21813040825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1231356 (or 1231351 counting only the distinct ones).

The product of its (nonzero) digits is 15360, while the sum is 34.

The spelling of 21813040825 in words is "twenty-one billion, eight hundred thirteen million, forty thousand, eight hundred twenty-five".