142123991 has 4 divisors (see below), whose sum is σ = 142637352. Its totient is φ = 141610632.

The previous prime is 142123973. The next prime is 142123997. The reversal of 142123991 is 199321241.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-142123991 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 (142123997) 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, 256265 + ... + 256818.

It is an arithmetic number, because the mean of its divisors is an integer number (35659338).

Almost surely, 2^142123991 is an apocalyptic number.

142123991 is a deficient number, since it is larger than the sum of its proper divisors (513361).

142123991 is an equidigital number, since it uses as much as digits as its factorization.

142123991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 513360.

The product of its digits is 3888, while the sum is 32.

The square root of 142123991 is about 11921.5766994135. The cubic root of 142123991 is about 521.8621487794.

The spelling of 142123991 in words is "one hundred forty-two million, one hundred twenty-three thousand, nine hundred ninety-one".