635984021 has 2 divisors, whose sum is σ = 635984022. Its totient is φ = 635984020.

The previous prime is 635983981. The next prime is 635984053. The reversal of 635984021 is 120489536.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 327103396 + 308880625 = 18086^2 + 17575^2 .

It is a cyclic number.

It is not a de Polignac number, because 635984021 - 2²⁶ = 568875157 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (635984081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 317992010 + 317992011.

It is an arithmetic number, because the mean of its divisors is an integer number (317992011).

Almost surely, 2^635984021 is an apocalyptic number.

It is an amenable number.

635984021 is a deficient number, since it is larger than the sum of its proper divisors (1).

635984021 is an equidigital number, since it uses as much as digits as its factorization.

635984021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 51840, while the sum is 38.

The square root of 635984021 is about 25218.7236195649. The cubic root of 635984021 is about 859.9675582678.

The spelling of 635984021 in words is "six hundred thirty-five million, nine hundred eighty-four thousand, twenty-one".