21275686477 has 4 divisors (see below), whose sum is σ = 21961998976. Its totient is φ = 20589373980.

The previous prime is 21275686463. The next prime is 21275686483. The reversal of 21275686477 is 77468657212.

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 21275686477 - 2⁷ = 21275686349 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 (21275680477) 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, 343156203 + ... + 343156264.

It is an arithmetic number, because the mean of its divisors is an integer number (5490499744).

Almost surely, 2^21275686477 is an apocalyptic number.

It is an amenable number.

21275686477 is a deficient number, since it is larger than the sum of its proper divisors (686312499).

21275686477 is an equidigital number, since it uses as much as digits as its factorization.

21275686477 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 686312498.

The product of its digits is 7902720, while the sum is 55.

The spelling of 21275686477 in words is "twenty-one billion, two hundred seventy-five million, six hundred eighty-six thousand, four hundred seventy-seven".