21308771477 has 4 divisors (see below), whose sum is σ = 24352881696. Its totient is φ = 18264661260.

The previous prime is 21308771447. The next prime is 21308771483. The reversal of 21308771477 is 77417780312.

It is a happy number.

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 21308771477 - 2⁸ = 21308771221 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 (21308771437) 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, 1522055099 + ... + 1522055112.

It is an arithmetic number, because the mean of its divisors is an integer number (6088220424).

Almost surely, 2^21308771477 is an apocalyptic number.

It is an amenable number.

21308771477 is a deficient number, since it is larger than the sum of its proper divisors (3044110219).

21308771477 is an equidigital number, since it uses as much as digits as its factorization.

21308771477 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3044110218.

The product of its (nonzero) digits is 460992, while the sum is 47.

The spelling of 21308771477 in words is "twenty-one billion, three hundred eight million, seven hundred seventy-one thousand, four hundred seventy-seven".