21663398125 has 20 divisors (see below), whose sum is σ = 28247582880. Its totient is φ = 16577198000.

The previous prime is 21663398089. The next prime is 21663398161. The reversal of 21663398125 is 52189336612.

It is an interprime number because it is at equal distance from previous prime (21663398089) and next prime (21663398161).

It is not a de Polignac number, because 21663398125 - 2¹³ = 21663389933 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 (19) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 739135 + ... + 767884.

It is an arithmetic number, because the mean of its divisors is an integer number (1412379144).

Almost surely, 2^21663398125 is an apocalyptic number.

21663398125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21663398125 is a deficient number, since it is larger than the sum of its proper divisors (6584184755).

21663398125 is an equidigital number, since it uses as much as digits as its factorization.

21663398125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1507062 (or 1507047 counting only the distinct ones).

The product of its digits is 466560, while the sum is 46.

The spelling of 21663398125 in words is "twenty-one billion, six hundred sixty-three million, three hundred ninety-eight thousand, one hundred twenty-five".