16400781 has 12 divisors (see below), whose sum is σ = 24937120. Its totient is φ = 10358280.

The previous prime is 16400737. The next prime is 16400789. The reversal of 16400781 is 18700461.

It is a happy number.

16400781 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 16400781 - 2⁹ = 16400269 is a prime.

It is a super-2 number, since 2×16400781² = 537971234819922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16400789) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 47785 + ... + 48126.

Almost surely, 2^16400781 is an apocalyptic number.

It is an amenable number.

16400781 is a deficient number, since it is larger than the sum of its proper divisors (8536339).

16400781 is a wasteful number, since it uses less digits than its factorization.

16400781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95936 (or 95933 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 27.

The square root of 16400781 is about 4049.7877722172. The cubic root of 16400781 is about 254.0708515430.

The spelling of 16400781 in words is "sixteen million, four hundred thousand, seven hundred eighty-one".