951991 has 4 divisors (see below), whose sum is σ = 955800. Its totient is φ = 948184.

The previous prime is 951967. The next prime is 951997. The reversal of 951991 is 199159.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199159 = 79 ⋅2521.

It is a cyclic number.

It is not a de Polignac number, because 951991 - 2⁵ = 951959 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (951997) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1501 + ... + 2038.

It is an arithmetic number, because the mean of its divisors is an integer number (238950).

2⁹⁵¹⁹⁹¹ is an apocalyptic number.

951991 is a deficient number, since it is larger than the sum of its proper divisors (3809).

951991 is a wasteful number, since it uses less digits than its factorization.

951991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3808.

The product of its digits is 3645, while the sum is 34.

The square root of 951991 is about 975.7002613508. The cubic root of 951991 is about 98.3733846871.

The spelling of 951991 in words is "nine hundred fifty-one thousand, nine hundred ninety-one".