16405663 has 6 divisors (see below), whose sum is σ = 17427776. Its totient is φ = 15440352.

The previous prime is 16405657. The next prime is 16405667. The reversal of 16405663 is 36650461.

It is not a de Polignac number, because 16405663 - 2¹⁷ = 16274591 is a prime.

It is a super-3 number, since 3×16405663³ (a number of 23 digits) contains 333 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 (16405667) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 28095 + ... + 28672.

Almost surely, 2^16405663 is an apocalyptic number.

16405663 is a deficient number, since it is larger than the sum of its proper divisors (1022113).

16405663 is an equidigital number, since it uses as much as digits as its factorization.

16405663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56801 (or 56784 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 31.

The square root of 16405663 is about 4050.3904750036. The cubic root of 16405663 is about 254.0960586931.

The spelling of 16405663 in words is "sixteen million, four hundred five thousand, six hundred sixty-three".