3967561781 has 4 divisors (see below), whose sum is σ = 3971004012. Its totient is φ = 3964119552.

The previous prime is 3967561771. The next prime is 3967561831. The reversal of 3967561781 is 1871657693.

3967561781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1136364100 + 2831197681 = 33710^2 + 53209^2 .

It is a cyclic number.

It is not a de Polignac number, because 3967561781 - 2¹⁴ = 3967545397 is a prime.

It is a super-2 number, since 2×3967561781² = 31483092972103783922, 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 (3967561771) 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, 1719386 + ... + 1721691.

It is an arithmetic number, because the mean of its divisors is an integer number (992751003).

Almost surely, 2^3967561781 is an apocalyptic number.

It is an amenable number.

3967561781 is a deficient number, since it is larger than the sum of its proper divisors (3442231).

3967561781 is a wasteful number, since it uses less digits than its factorization.

3967561781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3442230.

The product of its digits is 1905120, while the sum is 53.

The square root of 3967561781 is about 62988.5845292621. The cubic root of 3967561781 is about 1583.0983613736.

The spelling of 3967561781 in words is "three billion, nine hundred sixty-seven million, five hundred sixty-one thousand, seven hundred eighty-one".