195720991 has 4 divisors (see below), whose sum is σ = 196037800. Its totient is φ = 195404184.

The previous prime is 195720977. The next prime is 195721021. The reversal of 195720991 is 199027591.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 195720991 - 2²⁵ = 162166559 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (195730991) 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, 157476 + ... + 158713.

It is an arithmetic number, because the mean of its divisors is an integer number (49009450).

Almost surely, 2^195720991 is an apocalyptic number.

195720991 is a deficient number, since it is larger than the sum of its proper divisors (316809).

195720991 is an equidigital number, since it uses as much as digits as its factorization.

195720991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 316808.

The product of its (nonzero) digits is 51030, while the sum is 43.

The square root of 195720991 is about 13990.0318441382. The cubic root of 195720991 is about 580.6028126183.

The spelling of 195720991 in words is "one hundred ninety-five million, seven hundred twenty thousand, nine hundred ninety-one".