21390657825 has 24 divisors (see below), whose sum is σ = 35402207328. Its totient is φ = 11396634880.

The previous prime is 21390657811. The next prime is 21390657829. The reversal of 21390657825 is 52875609312.

It is not a de Polignac number, because 21390657825 - 2⁹ = 21390657313 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21390657829) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 72687 + ... + 219236.

It is an arithmetic number, because the mean of its divisors is an integer number (1475091972).

Almost surely, 2^21390657825 is an apocalyptic number.

21390657825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21390657825 is a deficient number, since it is larger than the sum of its proper divisors (14011549503).

21390657825 is a wasteful number, since it uses less digits than its factorization.

21390657825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 292913 (or 292908 counting only the distinct ones).

The product of its (nonzero) digits is 907200, while the sum is 48.

The spelling of 21390657825 in words is "twenty-one billion, three hundred ninety million, six hundred fifty-seven thousand, eight hundred twenty-five".