21951091799 has 32 divisors (see below), whose sum is σ = 28552527360. Its totient is φ = 16387920000.

The previous prime is 21951091769. The next prime is 21951091807. The reversal of 21951091799 is 99719015912.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21951091799 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21951091799.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21951091769) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 408689 + ... + 459269.

It is an arithmetic number, because the mean of its divisors is an integer number (892266480).

Almost surely, 2^21951091799 is an apocalyptic number.

21951091799 is a deficient number, since it is larger than the sum of its proper divisors (6601435561).

21951091799 is a wasteful number, since it uses less digits than its factorization.

21951091799 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50871.

The product of its (nonzero) digits is 459270, while the sum is 53.

The spelling of 21951091799 in words is "twenty-one billion, nine hundred fifty-one million, ninety-one thousand, seven hundred ninety-nine".