991623198 has 32 divisors (see below), whose sum is σ = 2027539872. Its totient is φ = 323222400.

The previous prime is 991623131. The next prime is 991623223. The reversal of 991623198 is 891326199.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 55488 + ... + 71148.

It is an arithmetic number, because the mean of its divisors is an integer number (63360621).

Almost surely, 2^991623198 is an apocalyptic number.

991623198 is an abundant number, since it is smaller than the sum of its proper divisors (1035916674).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

991623198 is a wasteful number, since it uses less digits than its factorization.

991623198 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15900.

The product of its digits is 209952, while the sum is 48.

The square root of 991623198 is about 31490.0491901807. The cubic root of 991623198 is about 997.1998994215.

The spelling of 991623198 in words is "nine hundred ninety-one million, six hundred twenty-three thousand, one hundred ninety-eight".