3643655681 has 2 divisors, whose sum is σ = 3643655682. Its totient is φ = 3643655680.

The previous prime is 3643655657. The next prime is 3643655689. The reversal of 3643655681 is 1865563463.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3001286656 + 642369025 = 54784^2 + 25345^2 .

It is a cyclic number.

It is not a de Polignac number, because 3643655681 - 2²⁶ = 3576546817 is a prime.

It is a super-2 number, since 2×3643655681² = 26552453443367147522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (3643655689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1821827840 + 1821827841.

It is an arithmetic number, because the mean of its divisors is an integer number (1821827841).

Almost surely, 2^3643655681 is an apocalyptic number.

It is an amenable number.

3643655681 is a deficient number, since it is larger than the sum of its proper divisors (1).

3643655681 is an equidigital number, since it uses as much as digits as its factorization.

3643655681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1555200, while the sum is 47.

The square root of 3643655681 is about 60362.7010744218. The cubic root of 3643655681 is about 1538.7891309543.

The spelling of 3643655681 in words is "three billion, six hundred forty-three million, six hundred fifty-five thousand, six hundred eighty-one".