991002051 has 24 divisors (see below), whose sum is σ = 1542742656. Its totient is φ = 609379200.

The previous prime is 991002041. The next prime is 991002059. The reversal of 991002051 is 150200199.

It is a happy number.

It is not a de Polignac number, because 991002051 - 2⁶ = 991001987 is a prime.

It is not an unprimeable number, because it can be changed into a prime (991002059) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 208366 + ... + 213068.

It is an arithmetic number, because the mean of its divisors is an integer number (64280944).

Almost surely, 2^991002051 is an apocalyptic number.

991002051 is a deficient number, since it is larger than the sum of its proper divisors (551740605).

991002051 is a wasteful number, since it uses less digits than its factorization.

991002051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6523 (or 6520 counting only the distinct ones).

The product of its (nonzero) digits is 810, while the sum is 27.

The square root of 991002051 is about 31480.1850534586. The cubic root of 991002051 is about 996.9916425274.

The spelling of 991002051 in words is "nine hundred ninety-one million, two thousand, fifty-one".