400606991 has 16 divisors (see below), whose sum is σ = 421977600. Its totient is φ = 379965888.

The previous prime is 400606981. The next prime is 400607047. The reversal of 400606991 is 199606004.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-400606991 is a prime.

It is a super-2 number, since 2×400606991² = 320971922476148162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (400606901) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 201440 + ... + 203418.

It is an arithmetic number, because the mean of its divisors is an integer number (26373600).

Almost surely, 2^400606991 is an apocalyptic number.

400606991 is a deficient number, since it is larger than the sum of its proper divisors (21370609).

400606991 is a wasteful number, since it uses less digits than its factorization.

400606991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2158.

The product of its (nonzero) digits is 11664, while the sum is 35.

The square root of 400606991 is about 20015.1690225189. The cubic root of 400606991 is about 737.1788070283.

The spelling of 400606991 in words is "four hundred million, six hundred six thousand, nine hundred ninety-one".