156691001 has 4 divisors (see below), whose sum is σ = 156716112. Its totient is φ = 156665892.

The previous prime is 156690991. The next prime is 156691021. The reversal of 156691001 is 100196651.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-156691001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (156691021) 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, 4826 + ... + 18348.

It is an arithmetic number, because the mean of its divisors is an integer number (39179028).

Almost surely, 2^156691001 is an apocalyptic number.

It is an amenable number.

156691001 is a deficient number, since it is larger than the sum of its proper divisors (25111).

156691001 is a wasteful number, since it uses less digits than its factorization.

156691001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25110.

The product of its (nonzero) digits is 1620, while the sum is 29.

The square root of 156691001 is about 12517.6276106936. The cubic root of 156691001 is about 539.1149207150.

The spelling of 156691001 in words is "one hundred fifty-six million, six hundred ninety-one thousand, one".