86782678921 has 9 divisors (see below), whose sum is σ = 87715451349. Its totient is φ = 85859731584.

The previous prime is 86782678903. The next prime is 86782678951. The reversal of 86782678921 is 12987628768.

The square root of 86782678921 is 294589.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 9242707321 + 77539971600 = 96139^2 + 278460^2 .

It is not a de Polignac number, because 86782678921 - 2⁵ = 86782678889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (86782678951) 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 8 ways as a sum of consecutive naturals, for example, 28573615 + ... + 28576651.

It is an arithmetic number, because the mean of its divisors is an integer number (9746161261).

Almost surely, 2^86782678921 is an apocalyptic number.

86782678921 is the 294589-th square number.

86782678921 is the 147295-th centered octagonal number.

It is an amenable number.

86782678921 is a deficient number, since it is larger than the sum of its proper divisors (932772428).

86782678921 is an frugal number, since it uses more digits than its factorization.

86782678921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6268 (or 3134 counting only the distinct ones).

The product of its digits is 32514048, while the sum is 64.

Multiplying 86782678921 by its sum of digits (64), we get a square (5554091450944 = 2356712²).

It can be divided in two parts, 86782 and 678921, that added together give a triangular number (765703 = T₁₂₃₇).

The spelling of 86782678921 in words is "eighty-six billion, seven hundred eighty-two million, six hundred seventy-eight thousand, nine hundred twenty-one".