99991961 has 4 divisors (see below), whose sum is σ = 101686800. Its totient is φ = 98297124.

The previous prime is 99991951. The next prime is 99991981. The reversal of 99991961 is 16919999.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 99991961 - 2⁶ = 99991897 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (99991901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 847331 + ... + 847448.

It is an arithmetic number, because the mean of its divisors is an integer number (25421700).

Almost surely, 2^99991961 is an apocalyptic number.

It is an amenable number.

99991961 is a deficient number, since it is larger than the sum of its proper divisors (1694839).

99991961 is a wasteful number, since it uses less digits than its factorization.

99991961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1694838.

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

The square root of 99991961 is about 9999.5980419215. The cubic root of 99991961 is about 464.1464451171.

The spelling of 99991961 in words is "ninety-nine million, nine hundred ninety-one thousand, nine hundred sixty-one".