1191990979 has 2 divisors, whose sum is σ = 1191990980. Its totient is φ = 1191990978.

The previous prime is 1191990959. The next prime is 1191991007. The reversal of 1191990979 is 9790991911.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1191990979 - 2⁷ = 1191990851 is a prime.

It is not a weakly prime, because it can be changed into another prime (1191990949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 595995489 + 595995490.

It is an arithmetic number, because the mean of its divisors is an integer number (595995490).

Almost surely, 2^1191990979 is an apocalyptic number.

1191990979 is a deficient number, since it is larger than the sum of its proper divisors (1).

1191990979 is an equidigital number, since it uses as much as digits as its factorization.

1191990979 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 413343, while the sum is 55.

The square root of 1191990979 is about 34525.2223598922. Note that the first 3 decimals coincide. The cubic root of 1191990979 is about 1060.2891637232.

The spelling of 1191990979 in words is "one billion, one hundred ninety-one million, nine hundred ninety thousand, nine hundred seventy-nine".