406697991 has 24 divisors (see below), whose sum is σ = 642711024. Its totient is φ = 228009600.

The previous prime is 406697989. The next prime is 406698031. The reversal of 406697991 is 199796604.

It is not a de Polignac number, because 406697991 - 2¹ = 406697989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (406697911) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18310 + ... + 33891.

It is an arithmetic number, because the mean of its divisors is an integer number (26779626).

Almost surely, 2^406697991 is an apocalyptic number.

406697991 is a deficient number, since it is larger than the sum of its proper divisors (236013033).

406697991 is a wasteful number, since it uses less digits than its factorization.

406697991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52271 (or 52264 counting only the distinct ones).

The product of its (nonzero) digits is 734832, while the sum is 51.

The square root of 406697991 is about 20166.7545976044. The cubic root of 406697991 is about 740.8961574157.

The spelling of 406697991 in words is "four hundred six million, six hundred ninety-seven thousand, nine hundred ninety-one".