991925906 has 4 divisors (see below), whose sum is σ = 1487888862. Its totient is φ = 495962952.

The previous prime is 991925887. The next prime is 991925917. The reversal of 991925906 is 609529199.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 609529199 = 109 ⋅5592011.

It can be written as a sum of positive squares in only one way, i.e., 958459681 + 33466225 = 30959^2 + 5785^2 .

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 as a sum of consecutive naturals, namely, 247981475 + ... + 247981478.

Almost surely, 2^991925906 is an apocalyptic number.

991925906 is a deficient number, since it is larger than the sum of its proper divisors (495962956).

991925906 is a wasteful number, since it uses less digits than its factorization.

991925906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 495962955.

The product of its (nonzero) digits is 393660, while the sum is 50.

The square root of 991925906 is about 31494.8552306563. The cubic root of 991925906 is about 997.3013592224.

The spelling of 991925906 in words is "nine hundred ninety-one million, nine hundred twenty-five thousand, nine hundred six".