123581621 has 4 divisors (see below), whose sum is σ = 123938112. Its totient is φ = 123225132.

The previous prime is 123581581. The next prime is 123581629. The reversal of 123581621 is 126185321.

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 an emirpimes, since its reverse is a distinct semiprime: 126185321 = 67 ⋅1883363.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-123581621 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 (123581629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 177725 + ... + 178418.

It is an arithmetic number, because the mean of its divisors is an integer number (30984528).

Almost surely, 2^123581621 is an apocalyptic number.

It is an amenable number.

123581621 is a deficient number, since it is larger than the sum of its proper divisors (356491).

123581621 is an equidigital number, since it uses as much as digits as its factorization.

123581621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 356490.

The product of its digits is 2880, while the sum is 29.

The square root of 123581621 is about 11116.7270812951. The cubic root of 123581621 is about 498.1016295007.

The spelling of 123581621 in words is "one hundred twenty-three million, five hundred eighty-one thousand, six hundred twenty-one".