21109807997 has 16 divisors (see below), whose sum is σ = 22548049920. Its totient is φ = 19716913392.

The previous prime is 21109807973. The next prime is 21109808011. The reversal of 21109807997 is 79970890112.

It is not a de Polignac number, because 21109807997 - 2⁶ = 21109807933 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 (21109807907) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 452318 + ... + 496800.

It is an arithmetic number, because the mean of its divisors is an integer number (1409253120).

Almost surely, 2^21109807997 is an apocalyptic number.

It is an amenable number.

21109807997 is a deficient number, since it is larger than the sum of its proper divisors (1438241923).

21109807997 is a wasteful number, since it uses less digits than its factorization.

21109807997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44992.

The product of its (nonzero) digits is 571536, while the sum is 53.

The spelling of 21109807997 in words is "twenty-one billion, one hundred nine million, eight hundred seven thousand, nine hundred ninety-seven".