21276717961 has 4 divisors (see below), whose sum is σ = 21283916292. Its totient is φ = 21269519632.

The previous prime is 21276717953. The next prime is 21276717991. The reversal of 21276717961 is 16971767212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1532252736 + 19744465225 = 39144^2 + 140515^2 .

It is a cyclic number.

It is not a de Polignac number, because 21276717961 - 2³ = 21276717953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21276717911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3594730 + ... + 3600643.

It is an arithmetic number, because the mean of its divisors is an integer number (5320979073).

Almost surely, 2^21276717961 is an apocalyptic number.

It is an amenable number.

21276717961 is a deficient number, since it is larger than the sum of its proper divisors (7198331).

21276717961 is an equidigital number, since it uses as much as digits as its factorization.

21276717961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7198330.

The product of its digits is 444528, while the sum is 49.

The spelling of 21276717961 in words is "twenty-one billion, two hundred seventy-six million, seven hundred seventeen thousand, nine hundred sixty-one".