642221117 has 2 divisors, whose sum is σ = 642221118. Its totient is φ = 642221116.

The previous prime is 642221101. The next prime is 642221137. The reversal of 642221117 is 711122246.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 504182116 + 138039001 = 22454^2 + 11749^2 .

It is a cyclic number.

It is not a de Polignac number, because 642221117 - 2⁴ = 642221101 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 (642221137) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321110558 + 321110559.

It is an arithmetic number, because the mean of its divisors is an integer number (321110559).

Almost surely, 2^642221117 is an apocalyptic number.

It is an amenable number.

642221117 is a deficient number, since it is larger than the sum of its proper divisors (1).

642221117 is an equidigital number, since it uses as much as digits as its factorization.

642221117 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1344, while the sum is 26.

The square root of 642221117 is about 25342.0819389410. The cubic root of 642221117 is about 862.7696523530.

The spelling of 642221117 in words is "six hundred forty-two million, two hundred twenty-one thousand, one hundred seventeen".