21279477657 has 8 divisors (see below), whose sum is σ = 28411033120. Its totient is φ = 14167120320.

The previous prime is 21279477631. The next prime is 21279477679. The reversal of 21279477657 is 75677497212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21279477657 - 2¹⁰ = 21279476633 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21279477597 and 21279477606.

It is not an unprimeable number, because it can be changed into a prime (21279470657) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4796944 + ... + 4801377.

It is an arithmetic number, because the mean of its divisors is an integer number (3551379140).

Almost surely, 2^21279477657 is an apocalyptic number.

It is an amenable number.

21279477657 is a deficient number, since it is larger than the sum of its proper divisors (7131555463).

21279477657 is an equidigital number, since it uses as much as digits as its factorization.

21279477657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9599063.

The product of its digits is 10372320, while the sum is 57.

The spelling of 21279477657 in words is "twenty-one billion, two hundred seventy-nine million, four hundred seventy-seven thousand, six hundred fifty-seven".