406891661 has 6 divisors (see below), whose sum is σ = 447244686. Its totient is φ = 369901400.

The previous prime is 406891657. The next prime is 406891691. The reversal of 406891661 is 166198604.

It can be written as a sum of positive squares in only one way, i.e., 372258436 + 34633225 = 19294^2 + 5885^2 .

It is not a de Polignac number, because 406891661 - 2² = 406891657 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 (406891601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1681250 + ... + 1681491.

It is an arithmetic number, because the mean of its divisors is an integer number (74540781).

Almost surely, 2^406891661 is an apocalyptic number.

It is an amenable number.

406891661 is a deficient number, since it is larger than the sum of its proper divisors (40353025).

406891661 is a wasteful number, since it uses less digits than its factorization.

406891661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3362763 (or 3362752 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 41.

The square root of 406891661 is about 20171.5557406959. Note that the first 3 decimals coincide. The cubic root of 406891661 is about 741.0137439225.

The spelling of 406891661 in words is "four hundred six million, eight hundred ninety-one thousand, six hundred sixty-one".