21877695491 has 4 divisors (see below), whose sum is σ = 21906145800. Its totient is φ = 21849245184.

The previous prime is 21877695461. The next prime is 21877695493. The reversal of 21877695491 is 19459677812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21877695491 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21877695491.

It is not an unprimeable number, because it can be changed into a prime (21877695493) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14224001 + ... + 14225538.

It is an arithmetic number, because the mean of its divisors is an integer number (5476536450).

Almost surely, 2^21877695491 is an apocalyptic number.

21877695491 is a deficient number, since it is larger than the sum of its proper divisors (28450309).

21877695491 is an equidigital number, since it uses as much as digits as its factorization.

21877695491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28450308.

The product of its digits is 7620480, while the sum is 59.

The spelling of 21877695491 in words is "twenty-one billion, eight hundred seventy-seven million, six hundred ninety-five thousand, four hundred ninety-one".