123012721 has 4 divisors (see below), whose sum is σ = 132475252. Its totient is φ = 113550192.

The previous prime is 123012719. The next prime is 123012733. The reversal of 123012721 is 127210321.

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 12531600 + 110481121 = 3540^2 + 10511^2 .

It is a cyclic number.

It is not a de Polignac number, because 123012721 - 2¹ = 123012719 is a prime.

It is a super-3 number, since 3×123012721³ (a number of 25 digits) contains 333 as substring.

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

It is not an unprimeable number, because it can be changed into a prime (123042721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4731246 + ... + 4731271.

It is an arithmetic number, because the mean of its divisors is an integer number (33118813).

Almost surely, 2^123012721 is an apocalyptic number.

It is an amenable number.

123012721 is a deficient number, since it is larger than the sum of its proper divisors (9462531).

123012721 is an equidigital number, since it uses as much as digits as its factorization.

123012721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9462530.

The product of its (nonzero) digits is 168, while the sum is 19.

The square root of 123012721 is about 11091.1099985529. The cubic root of 123012721 is about 497.3361274372.

The spelling of 123012721 in words is "one hundred twenty-three million, twelve thousand, seven hundred twenty-one".