149971691 has 4 divisors (see below), whose sum is σ = 150000312. Its totient is φ = 149943072.

The previous prime is 149971639. The next prime is 149971699. The reversal of 149971691 is 196179941.

149971691 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 196179941 = 89 ⋅2204269.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-149971691 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (149971699) 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, 3950 + ... + 17763.

It is an arithmetic number, because the mean of its divisors is an integer number (37500078).

Almost surely, 2^149971691 is an apocalyptic number.

149971691 is a deficient number, since it is larger than the sum of its proper divisors (28621).

149971691 is an equidigital number, since it uses as much as digits as its factorization.

149971691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28620.

The product of its digits is 122472, while the sum is 47.

The square root of 149971691 is about 12246.2929492969. The cubic root of 149971691 is about 531.2958571534.

The spelling of 149971691 in words is "one hundred forty-nine million, nine hundred seventy-one thousand, six hundred ninety-one".