21276323561 has 16 divisors (see below), whose sum is σ = 22039691520. Its totient is φ = 20525374080.

The previous prime is 21276323533. The next prime is 21276323567. The reversal of 21276323561 is 16532367212.

It is a de Polignac number, because none of the positive numbers 2^k-21276323561 is a prime.

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21276323567) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2332736 + ... + 2341838.

It is an arithmetic number, because the mean of its divisors is an integer number (1377480720).

Almost surely, 2^21276323561 is an apocalyptic number.

It is an amenable number.

21276323561 is a deficient number, since it is larger than the sum of its proper divisors (763367959).

21276323561 is a wasteful number, since it uses less digits than its factorization.

21276323561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9776.

The product of its digits is 90720, while the sum is 38.

The spelling of 21276323561 in words is "twenty-one billion, two hundred seventy-six million, three hundred twenty-three thousand, five hundred sixty-one".