21278417960 has 16 divisors (see below), whose sum is σ = 47876440500. Its totient is φ = 8511367168.

The previous prime is 21278417939. The next prime is 21278417987. The reversal of 21278417960 is 6971487212.

It can be written as a sum of positive squares in 2 ways, for example, as 20598564484 + 679853476 = 143522^2 + 26074^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 265980185 + ... + 265980264.

Almost surely, 2^21278417960 is an apocalyptic number.

21278417960 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21278417960 is an abundant number, since it is smaller than the sum of its proper divisors (26598022540).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21278417960 is a wasteful number, since it uses less digits than its factorization.

21278417960 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 531960460 (or 531960456 counting only the distinct ones).

The product of its (nonzero) digits is 338688, while the sum is 47.

The spelling of 21278417960 in words is "twenty-one billion, two hundred seventy-eight million, four hundred seventeen thousand, nine hundred sixty".