623172991 has 4 divisors (see below), whose sum is σ = 712197712. Its totient is φ = 534148272.

The previous prime is 623172989. The next prime is 623172997. The reversal of 623172991 is 199271326.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199271326 = 2 ⋅99635663.

It is not a de Polignac number, because 623172991 - 2¹ = 623172989 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 (623172997) 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, 44512350 + ... + 44512363.

It is an arithmetic number, because the mean of its divisors is an integer number (178049428).

Almost surely, 2^623172991 is an apocalyptic number.

623172991 is a deficient number, since it is larger than the sum of its proper divisors (89024721).

623172991 is an equidigital number, since it uses as much as digits as its factorization.

623172991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89024720.

The product of its digits is 40824, while the sum is 40.

The square root of 623172991 is about 24963.4330772031. The cubic root of 623172991 is about 854.1540558514.

The spelling of 623172991 in words is "six hundred twenty-three million, one hundred seventy-two thousand, nine hundred ninety-one".