27878646961 has 27 divisors (see below), whose sum is σ = 31461809547. Its totient is φ = 24684696960.

The previous prime is 27878646931. The next prime is 27878646967. The reversal of 27878646961 is 16964687872.

The square root of 27878646961 is 166969.

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

It can be written as a sum of positive squares in only one way, i.e., 11326280625 + 16552366336 = 106425^2 + 128656^2 .

It is not a de Polignac number, because 27878646961 - 2¹⁵ = 27878614193 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 27878646893 and 27878646902.

It is not an unprimeable number, because it can be changed into a prime (27878646967) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 78976161 + ... + 78976513.

Almost surely, 2^27878646961 is an apocalyptic number.

27878646961 is the 166969-th square number.

27878646961 is the 83485-th centered octagonal number.

It is an amenable number.

27878646961 is a deficient number, since it is larger than the sum of its proper divisors (3583162586).

27878646961 is an frugal number, since it uses more digits than its factorization.

27878646961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 814 (or 407 counting only the distinct ones).

The product of its digits is 48771072, while the sum is 64.

Multiplying 27878646961 by its sum of digits (64), we get a square (1784233405504 = 1335752²).

The spelling of 27878646961 in words is "twenty-seven billion, eight hundred seventy-eight million, six hundred forty-six thousand, nine hundred sixty-one".