21356374525 has 24 divisors (see below), whose sum is σ = 28141044840. Its totient is φ = 16021954560.

The previous prime is 21356374519. The next prime is 21356374591. The reversal of 21356374525 is 52547365312.

It is a happy number.

It can be written as a sum of positive squares in 12 ways, for example, as 1192942521 + 20163432004 = 34539^2 + 141998^2 .

It is not a de Polignac number, because 21356374525 - 2⁵ = 21356374493 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 27021 + ... + 208429.

It is an arithmetic number, because the mean of its divisors is an integer number (1172543535).

Almost surely, 2^21356374525 is an apocalyptic number.

21356374525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21356374525 is a deficient number, since it is larger than the sum of its proper divisors (6784670315).

21356374525 is a wasteful number, since it uses less digits than its factorization.

21356374525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 181713 (or 181708 counting only the distinct ones).

The product of its digits is 756000, while the sum is 43.

The spelling of 21356374525 in words is "twenty-one billion, three hundred fifty-six million, three hundred seventy-four thousand, five hundred twenty-five".