10156991 has 4 divisors (see below), whose sum is σ = 10938312. Its totient is φ = 9375672.

The previous prime is 10156957. The next prime is 10157023. The reversal of 10156991 is 19965101.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19965101 = 13 ⋅1535777.

It is a cyclic number.

It is not a de Polignac number, because 10156991 - 2¹⁰ = 10155967 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 (10156691) 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, 390641 + ... + 390666.

It is an arithmetic number, because the mean of its divisors is an integer number (2734578).

Almost surely, 2^10156991 is an apocalyptic number.

10156991 is a deficient number, since it is larger than the sum of its proper divisors (781321).

10156991 is an equidigital number, since it uses as much as digits as its factorization.

10156991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 781320.

The product of its (nonzero) digits is 2430, while the sum is 32.

The square root of 10156991 is about 3187.0034515199. The cubic root of 10156991 is about 216.5650429409.

The spelling of 10156991 in words is "ten million, one hundred fifty-six thousand, nine hundred ninety-one".