406405665 has 24 divisors (see below), whose sum is σ = 707197608. Its totient is φ = 215900160.

The previous prime is 406405661. The next prime is 406405711. The reversal of 406405665 is 566504604.

It is a happy number.

406405665 is a `hidden beast` number, since 4 + 0 + 640 + 5 + 6 + 6 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 133263936 + 273141729 = 11544^2 + 16527^2 .

It is not a de Polignac number, because 406405665 - 2² = 406405661 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (406405661) 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, 6006 + ... + 29135.

It is an arithmetic number, because the mean of its divisors is an integer number (29466567).

Almost surely, 2^406405665 is an apocalyptic number.

406405665 is a gapful number since it is divisible by the number (45) formed by its first and last digit.

It is an amenable number.

406405665 is a deficient number, since it is larger than the sum of its proper divisors (300791943).

406405665 is a wasteful number, since it uses less digits than its factorization.

406405665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35409 (or 35406 counting only the distinct ones).

The product of its (nonzero) digits is 86400, while the sum is 36.

The square root of 406405665 is about 20159.5055742942. The cubic root of 406405665 is about 740.7186013196.

The spelling of 406405665 in words is "four hundred six million, four hundred five thousand, six hundred sixty-five".