21991944526 has 16 divisors (see below), whose sum is σ = 33515599824. Its totient is φ = 10820424384.

The previous prime is 21991944503. The next prime is 21991944563. The reversal of 21991944526 is 62544919912.

It is a super-2 number, since 2×21991944526² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 41596 + ... + 213808.

It is an arithmetic number, because the mean of its divisors is an integer number (2094724989).

Almost surely, 2^21991944526 is an apocalyptic number.

21991944526 is a deficient number, since it is larger than the sum of its proper divisors (11523655298).

21991944526 is a wasteful number, since it uses less digits than its factorization.

21991944526 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173235.

The product of its digits is 1399680, while the sum is 52.

The spelling of 21991944526 in words is "twenty-one billion, nine hundred ninety-one million, nine hundred forty-four thousand, five hundred twenty-six".