21253801825 has 12 divisors (see below), whose sum is σ = 26412397420. Its totient is φ = 16965826560.

The previous prime is 21253801819. The next prime is 21253801853. The reversal of 21253801825 is 52810835212.

It can be written as a sum of positive squares in 6 ways, for example, as 853107264 + 20400694561 = 29208^2 + 142831^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21253801825 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, 918720 + ... + 941569.

Almost surely, 2^21253801825 is an apocalyptic number.

21253801825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21253801825 is a deficient number, since it is larger than the sum of its proper divisors (5158595595).

21253801825 is a wasteful number, since it uses less digits than its factorization.

21253801825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1860756 (or 1860751 counting only the distinct ones).

The product of its (nonzero) digits is 38400, while the sum is 37.

The spelling of 21253801825 in words is "twenty-one billion, two hundred fifty-three million, eight hundred one thousand, eight hundred twenty-five".