991901000 has 32 divisors (see below), whose sum is σ = 2321050680. Its totient is φ = 396760000.

The previous prime is 991900997. The next prime is 991901033. The reversal of 991901000 is 109199.

It can be written as a sum of positive squares in 4 ways, for example, as 373185124 + 618715876 = 19318^2 + 24874^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 494951 + ... + 496950.

Almost surely, 2^991901000 is an apocalyptic number.

It is an amenable number.

991901000 is an abundant number, since it is smaller than the sum of its proper divisors (1329149680).

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

991901000 is a wasteful number, since it uses less digits than its factorization.

991901000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 991922 (or 991908 counting only the distinct ones).

The product of its (nonzero) digits is 729, while the sum is 29.

The square root of 991901000 is about 31494.4598302622. The cubic root of 991901000 is about 997.2930121623.

The spelling of 991901000 in words is "nine hundred ninety-one million, nine hundred one thousand".