21975187477 has 4 divisors (see below), whose sum is σ = 21981640896. Its totient is φ = 21968734060.

The previous prime is 21975187469. The next prime is 21975187489. The reversal of 21975187477 is 77478157912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21975187477 - 2³ = 21975187469 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 (21975127477) 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, 3221599 + ... + 3228412.

It is an arithmetic number, because the mean of its divisors is an integer number (5495410224).

Almost surely, 2^21975187477 is an apocalyptic number.

It is an amenable number.

21975187477 is a deficient number, since it is larger than the sum of its proper divisors (6453419).

21975187477 is an equidigital number, since it uses as much as digits as its factorization.

21975187477 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6453418.

The product of its digits is 6914880, while the sum is 58.

The spelling of 21975187477 in words is "twenty-one billion, nine hundred seventy-five million, one hundred eighty-seven thousand, four hundred seventy-seven".