3634643981 has 2 divisors, whose sum is σ = 3634643982. Its totient is φ = 3634643980.

The previous prime is 3634643963. The next prime is 3634644053. The reversal of 3634643981 is 1893464363.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3631147081 + 3496900 = 60259^2 + 1870^2 .

It is a cyclic number.

It is not a de Polignac number, because 3634643981 - 2¹⁸ = 3634381837 is a prime.

It is a super-2 number, since 2×3634643981² = 26421273737239056722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3634643941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1817321990 + 1817321991.

It is an arithmetic number, because the mean of its divisors is an integer number (1817321991).

Almost surely, 2^3634643981 is an apocalyptic number.

It is an amenable number.

3634643981 is a deficient number, since it is larger than the sum of its proper divisors (1).

3634643981 is an equidigital number, since it uses as much as digits as its factorization.

3634643981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1119744, while the sum is 47.

The square root of 3634643981 is about 60288.0086003842. The cubic root of 3634643981 is about 1537.5194762201.

The spelling of 3634643981 in words is "three billion, six hundred thirty-four million, six hundred forty-three thousand, nine hundred eighty-one".