4000781 has 8 divisors (see below), whose sum is σ = 4264704. Its totient is φ = 3744400.

The previous prime is 4000751. The next prime is 4000813. The reversal of 4000781 is 1870004.

It is a happy number.

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

It is a de Polignac number, because none of the positive numbers 2^k-4000781 is a prime.

It is a super-2 number, since 2×4000781² = 32012497219922, 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 (4000741) 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, 770 + ... + 2931.

It is an arithmetic number, because the mean of its divisors is an integer number (533088).

Almost surely, 2^4000781 is an apocalyptic number.

It is an amenable number.

4000781 is a deficient number, since it is larger than the sum of its proper divisors (263923).

4000781 is a wasteful number, since it uses less digits than its factorization.

4000781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3771.

The product of its (nonzero) digits is 224, while the sum is 20.

The square root of 4000781 is about 2000.1952404703. The cubic root of 4000781 is about 158.7504358597.

Adding to 4000781 its reverse (1870004), we get a palindrome (5870785).

The spelling of 4000781 in words is "four million, seven hundred eighty-one", and thus it is an aban number.