123412721 has 4 divisors (see below), whose sum is σ = 123596772. Its totient is φ = 123228672.

The previous prime is 123412703. The next prime is 123412759. The reversal of 123412721 is 127214321.

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

It can be written as a sum of positive squares in 2 ways, for example, as 14440000 + 108972721 = 3800^2 + 10439^2 .

It is a cyclic number.

It is not a de Polignac number, because 123412721 - 2¹⁰ = 123411697 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (123412781) 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, 91016 + ... + 92361.

It is an arithmetic number, because the mean of its divisors is an integer number (30899193).

Almost surely, 2^123412721 is an apocalyptic number.

It is an amenable number.

123412721 is a deficient number, since it is larger than the sum of its proper divisors (184051).

123412721 is an equidigital number, since it uses as much as digits as its factorization.

123412721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 184050.

The product of its digits is 672, while the sum is 23.

The square root of 123412721 is about 11109.1278235512. The cubic root of 123412721 is about 497.8746062038.

The spelling of 123412721 in words is "one hundred twenty-three million, four hundred twelve thousand, seven hundred twenty-one".