278877991921 has 9 divisors (see below), whose sum is σ = 279847217433. Its totient is φ = 277912117140.

The previous prime is 278877991831. The next prime is 278877991933. The reversal of 278877991921 is 129199778872.

The square root of 278877991921 is 528089.

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

It is not a de Polignac number, because 278877991921 - 2⁷ = 278877991793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (278877991321) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 189583216 + ... + 189584686.

Almost surely, 2^278877991921 is an apocalyptic number.

278877991921 is the 528089-th square number.

278877991921 is the 264045-th centered octagonal number.

It is an amenable number.

278877991921 is a deficient number, since it is larger than the sum of its proper divisors (969225512).

278877991921 is an frugal number, since it uses more digits than its factorization.

278877991921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3660 (or 1830 counting only the distinct ones).

The product of its digits is 64012032, while the sum is 70.

The spelling of 278877991921 in words is "two hundred seventy-eight billion, eight hundred seventy-seven million, nine hundred ninety-one thousand, nine hundred twenty-one".