478131991 has 2 divisors, whose sum is σ = 478131992. Its totient is φ = 478131990.

The previous prime is 478131977. The next prime is 478132001. The reversal of 478131991 is 199131874.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 478131991 - 2¹⁹ = 477607703 is a prime.

It is a super-2 number, since 2×478131991² = 457220401635248162, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (478131191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 239065995 + 239065996.

It is an arithmetic number, because the mean of its divisors is an integer number (239065996).

Almost surely, 2^478131991 is an apocalyptic number.

478131991 is a deficient number, since it is larger than the sum of its proper divisors (1).

478131991 is an equidigital number, since it uses as much as digits as its factorization.

478131991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54432, while the sum is 43.

The square root of 478131991 is about 21866.2294646334. The cubic root of 478131991 is about 781.9565122347.

The spelling of 478131991 in words is "four hundred seventy-eight million, one hundred thirty-one thousand, nine hundred ninety-one".