16405631 has 4 divisors (see below), whose sum is σ = 17897064. Its totient is φ = 14914200.

The previous prime is 16405621. The next prime is 16405633. The reversal of 16405631 is 13650461.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 16405631 - 2¹⁸ = 16143487 is a prime.

It is a super-2 number, since 2×16405631² = 538289457016322, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 16405631.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16405633) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 745700 + ... + 745721.

It is an arithmetic number, because the mean of its divisors is an integer number (4474266).

Almost surely, 2^16405631 is an apocalyptic number.

16405631 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

16405631 is a deficient number, since it is larger than the sum of its proper divisors (1491433).

16405631 is a wasteful number, since it uses less digits than its factorization.

16405631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1491432.

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 16405631 is about 4050.3865247653. The cubic root of 16405631 is about 254.0958934843.

The spelling of 16405631 in words is "sixteen million, four hundred five thousand, six hundred thirty-one".