423921991 has 4 divisors (see below), whose sum is σ = 426118672. Its totient is φ = 421725312.

The previous prime is 423921983. The next prime is 423922033. The reversal of 423921991 is 199129324.

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

It is a cyclic number.

It is not a de Polignac number, because 423921991 - 2³ = 423921983 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 (423928991) 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, 1098051 + ... + 1098436.

It is an arithmetic number, because the mean of its divisors is an integer number (106529668).

Almost surely, 2^423921991 is an apocalyptic number.

423921991 is a deficient number, since it is larger than the sum of its proper divisors (2196681).

423921991 is a wasteful number, since it uses less digits than its factorization.

423921991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2196680.

The product of its digits is 34992, while the sum is 40.

The square root of 423921991 is about 20589.3659688685. The cubic root of 423921991 is about 751.2110750474.

The spelling of 423921991 in words is "four hundred twenty-three million, nine hundred twenty-one thousand, nine hundred ninety-one".