642220637 has 2 divisors, whose sum is σ = 642220638. Its totient is φ = 642220636.

The previous prime is 642220619. The next prime is 642220703. The reversal of 642220637 is 736022246.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 630311236 + 11909401 = 25106^2 + 3451^2 .

It is a cyclic number.

It is not a de Polignac number, because 642220637 - 2¹² = 642216541 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 (642220937) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321110318 + 321110319.

It is an arithmetic number, because the mean of its divisors is an integer number (321110319).

Almost surely, 2^642220637 is an apocalyptic number.

It is an amenable number.

642220637 is a deficient number, since it is larger than the sum of its proper divisors (1).

642220637 is an equidigital number, since it uses as much as digits as its factorization.

642220637 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24192, while the sum is 32.

The square root of 642220637 is about 25342.0724685255. The cubic root of 642220637 is about 862.7694374065.

The spelling of 642220637 in words is "six hundred forty-two million, two hundred twenty thousand, six hundred thirty-seven".