21137782856 has 16 divisors (see below), whose sum is σ = 41000010300. Its totient is φ = 10204446784.

The previous prime is 21137782843. The next prime is 21137782859. The reversal of 21137782856 is 65828773112.

It can be written as a sum of positive squares in 2 ways, for example, as 21103372900 + 34409956 = 145270^2 + 5866^2 .

It is a super-3 number, since 3×21137782856³ (a number of 32 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21137782859) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45555335 + ... + 45555798.

Almost surely, 2^21137782856 is an apocalyptic number.

It is an amenable number.

21137782856 is a deficient number, since it is larger than the sum of its proper divisors (19862227444).

21137782856 is a wasteful number, since it uses less digits than its factorization.

21137782856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91111168 (or 91111164 counting only the distinct ones).

The product of its digits is 1128960, while the sum is 50.

The spelling of 21137782856 in words is "twenty-one billion, one hundred thirty-seven million, seven hundred eighty-two thousand, eight hundred fifty-six".