991900938 has 32 divisors (see below), whose sum is σ = 2400568704. Its totient is φ = 266729472.

The previous prime is 991900937. The next prime is 991900939. The reversal of 991900938 is 839009199.

It is an interprime number because it is at equal distance from previous prime (991900937) and next prime (991900939).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (991900937) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 693895 + ... + 695322.

It is an arithmetic number, because the mean of its divisors is an integer number (75017772).

Almost surely, 2^991900938 is an apocalyptic number.

991900938 is an abundant number, since it is smaller than the sum of its proper divisors (1408667766).

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

991900938 is a wasteful number, since it uses less digits than its factorization.

991900938 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1389246.

The product of its (nonzero) digits is 157464, while the sum is 48.

The square root of 991900938 is about 31494.4588459621. The cubic root of 991900938 is about 997.2929913832.

The spelling of 991900938 in words is "nine hundred ninety-one million, nine hundred thousand, nine hundred thirty-eight".