155623404457921 has 3 divisors (see below), whose sum is σ = 155623416932833. Its totient is φ = 155623391983010.

The previous prime is 155623404457849. The next prime is 155623404457933. The reversal of 155623404457921 is 129754404326551.

The square root of 155623404457921 is 12474911.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 155623404457921 - 2²⁹ = 155622867587009 is a prime.

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (155623414457921) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 6237456 + ... + 18712366.

Almost surely, 2^{155623404457921} is an apocalyptic number.

155623404457921 is the 12474911-st square number.

155623404457921 is the 6237456-th centered octagonal number.

It is an amenable number.

155623404457921 is a deficient number, since it is larger than the sum of its proper divisors (12474912).

155623404457921 is an frugal number, since it uses more digits than its factorization.

155623404457921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24949822 (or 12474911 counting only the distinct ones).

The product of its (nonzero) digits is 36288000, while the sum is 58.

The spelling of 155623404457921 in words is "one hundred fifty-five trillion, six hundred twenty-three billion, four hundred four million, four hundred fifty-seven thousand, nine hundred twenty-one".