21278949065 has 32 divisors (see below), whose sum is σ = 28419818112. Its totient is φ = 15163200000.

The previous prime is 21278949049. The next prime is 21278949071. The reversal of 21278949065 is 56094987212.

It is not a de Polignac number, because 21278949065 - 2⁴ = 21278949049 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (53).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21278948998 and 21278949016.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2359565 + ... + 2368565.

It is an arithmetic number, because the mean of its divisors is an integer number (888119316).

Almost surely, 2^21278949065 is an apocalyptic number.

It is an amenable number.

21278949065 is a deficient number, since it is larger than the sum of its proper divisors (7140869047).

21278949065 is a wasteful number, since it uses less digits than its factorization.

21278949065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9881.

The product of its (nonzero) digits is 2177280, while the sum is 53.

The spelling of 21278949065 in words is "twenty-one billion, two hundred seventy-eight million, nine hundred forty-nine thousand, sixty-five".