99779989 has 2 divisors, whose sum is σ = 99779990. Its totient is φ = 99779988.

The previous prime is 99779941. The next prime is 99780059. The reversal of 99779989 is 98997799.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 73667889 + 26112100 = 8583^2 + 5110^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-99779989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (99779189) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49889994 + 49889995.

It is an arithmetic number, because the mean of its divisors is an integer number (49889995).

Almost surely, 2^99779989 is an apocalyptic number.

It is an amenable number.

99779989 is a deficient number, since it is larger than the sum of its proper divisors (1).

99779989 is an equidigital number, since it uses as much as digits as its factorization.

99779989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 23147208, while the sum is 67.

The square root of 99779989 is about 9988.9933927298. The cubic root of 99779989 is about 463.8182332161.

The spelling of 99779989 in words is "ninety-nine million, seven hundred seventy-nine thousand, nine hundred eighty-nine".