21091997344 has 24 divisors (see below), whose sum is σ = 45299858688. Its totient is φ = 9587271360.

The previous prime is 21091997309. The next prime is 21091997351. The reversal of 21091997344 is 44379919012.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29959872 + ... + 29960575.

It is an arithmetic number, because the mean of its divisors is an integer number (1887494112).

Almost surely, 2^21091997344 is an apocalyptic number.

It is an amenable number.

21091997344 is an abundant number, since it is smaller than the sum of its proper divisors (24207861344).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21091997344 is a wasteful number, since it uses less digits than its factorization.

21091997344 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59920468 (or 59920460 counting only the distinct ones).

The product of its (nonzero) digits is 489888, while the sum is 49.

The spelling of 21091997344 in words is "twenty-one billion, ninety-one million, nine hundred ninety-seven thousand, three hundred forty-four".