16400581 has 4 divisors (see below), whose sum is σ = 16929664. Its totient is φ = 15871500.

The previous prime is 16400567. The next prime is 16400609. The reversal of 16400581 is 18500461.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 16400581 - 2⁷ = 16400453 is a prime.

It is a super-2 number, since 2×16400581² = 537958114275122, 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 (16403581) 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 3 ways as a sum of consecutive naturals, for example, 264495 + ... + 264556.

It is an arithmetic number, because the mean of its divisors is an integer number (4232416).

Almost surely, 2^16400581 is an apocalyptic number.

It is an amenable number.

16400581 is a deficient number, since it is larger than the sum of its proper divisors (529083).

16400581 is an equidigital number, since it uses as much as digits as its factorization.

16400581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 529082.

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 16400581 is about 4049.7630794900. The cubic root of 16400581 is about 254.0698187797.

The spelling of 16400581 in words is "sixteen million, four hundred thousand, five hundred eighty-one".