21565626838 has 16 divisors (see below), whose sum is σ = 36995479200. Its totient is φ = 9235953216.

The previous prime is 21565626821. The next prime is 21565626851. The reversal of 21565626838 is 83862656512.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 517413 + ... + 557536.

It is an arithmetic number, because the mean of its divisors is an integer number (2312217450).

Almost surely, 2^21565626838 is an apocalyptic number.

21565626838 is a deficient number, since it is larger than the sum of its proper divisors (15429852362).

21565626838 is a wasteful number, since it uses less digits than its factorization.

21565626838 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1076391.

The product of its digits is 4147200, while the sum is 52.

The spelling of 21565626838 in words is "twenty-one billion, five hundred sixty-five million, six hundred twenty-six thousand, eight hundred thirty-eight".