16406781 has 8 divisors (see below), whose sum is σ = 22581504. Its totient is φ = 10584960.

The previous prime is 16406777. The next prime is 16406813. The reversal of 16406781 is 18760461.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 16406781 - 2² = 16406777 is a prime.

It is a super-2 number, since 2×16406781² = 538364925563922, which contains 22 as substring.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16406701) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 88116 + ... + 88301.

It is an arithmetic number, because the mean of its divisors is an integer number (2822688).

Almost surely, 2^16406781 is an apocalyptic number.

It is an amenable number.

16406781 is a deficient number, since it is larger than the sum of its proper divisors (6174723).

16406781 is a wasteful number, since it uses less digits than its factorization.

16406781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 176451.

The product of its (nonzero) digits is 8064, while the sum is 33.

The square root of 16406781 is about 4050.5284840376. The cubic root of 16406781 is about 254.1018305403.

The spelling of 16406781 in words is "sixteen million, four hundred six thousand, seven hundred eighty-one".