21991944527 has 16 divisors (see below), whose sum is σ = 25190784000. Its totient is φ = 18807445728.

The previous prime is 21991944503. The next prime is 21991944563. The reversal of 21991944527 is 72544919912.

It is a cyclic number.

It is not a de Polignac number, because 21991944527 - 2⁶ = 21991944463 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21991944127) 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 15 ways as a sum of consecutive naturals, for example, 11000474 + ... + 11002472.

It is an arithmetic number, because the mean of its divisors is an integer number (1574424000).

Almost surely, 2^21991944527 is an apocalyptic number.

21991944527 is a deficient number, since it is larger than the sum of its proper divisors (3198839473).

21991944527 is a wasteful number, since it uses less digits than its factorization.

21991944527 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4790.

The product of its digits is 1632960, while the sum is 53.

The spelling of 21991944527 in words is "twenty-one billion, nine hundred ninety-one million, nine hundred forty-four thousand, five hundred twenty-seven".