1990878667 has 2 divisors, whose sum is σ = 1990878668. Its totient is φ = 1990878666.

The previous prime is 1990878613. The next prime is 1990878679. The reversal of 1990878667 is 7668780991.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1990878667 is a prime.

It is not a weakly prime, because it can be changed into another prime (1990878467) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995439333 + 995439334.

It is an arithmetic number, because the mean of its divisors is an integer number (995439334).

Almost surely, 2^1990878667 is an apocalyptic number.

1990878667 is a deficient number, since it is larger than the sum of its proper divisors (1).

1990878667 is an equidigital number, since it uses as much as digits as its factorization.

1990878667 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9144576, while the sum is 61.

The square root of 1990878667 is about 44619.2634071877. The cubic root of 1990878667 is about 1258.0027708139.

The spelling of 1990878667 in words is "one billion, nine hundred ninety million, eight hundred seventy-eight thousand, six hundred sixty-seven".