21279471777 has 24 divisors (see below), whose sum is σ = 30916274688. Its totient is φ = 14103669600.

The previous prime is 21279471769. The next prime is 21279471779. The reversal of 21279471777 is 77717497212.

It is not a de Polignac number, because 21279471777 - 2³ = 21279471769 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21279471779) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4503138 + ... + 4507860.

It is an arithmetic number, because the mean of its divisors is an integer number (1288178112).

Almost surely, 2^21279471777 is an apocalyptic number.

It is an amenable number.

21279471777 is a deficient number, since it is larger than the sum of its proper divisors (9636802911).

21279471777 is a wasteful number, since it uses less digits than its factorization.

21279471777 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7541 (or 7538 counting only the distinct ones).

The product of its digits is 2420208, while the sum is 54.

The spelling of 21279471777 in words is "twenty-one billion, two hundred seventy-nine million, four hundred seventy-one thousand, seven hundred seventy-seven".