99919961 has 2 divisors, whose sum is σ = 99919962. Its totient is φ = 99919960.

The previous prime is 99919957. The next prime is 99919969. The reversal of 99919961 is 16991999.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 59521225 + 40398736 = 7715^2 + 6356^2 .

It is a cyclic number.

It is not a de Polignac number, because 99919961 - 2² = 99919957 is a prime.

It is not a weakly prime, because it can be changed into another prime (99919969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49959980 + 49959981.

It is an arithmetic number, because the mean of its divisors is an integer number (49959981).

Almost surely, 2^99919961 is an apocalyptic number.

It is an amenable number.

99919961 is a deficient number, since it is larger than the sum of its proper divisors (1).

99919961 is an equidigital number, since it uses as much as digits as its factorization.

99919961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 354294, while the sum is 53.

The square root of 99919961 is about 9995.9972488992. The cubic root of 99919961 is about 464.0350142647.

The spelling of 99919961 in words is "ninety-nine million, nine hundred nineteen thousand, nine hundred sixty-one".