642221137 has 2 divisors, whose sum is σ = 642221138. Its totient is φ = 642221136.

The previous prime is 642221117. The next prime is 642221159. The reversal of 642221137 is 731122246.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 398361681 + 243859456 = 19959^2 + 15616^2 .

It is a cyclic number.

It is not a de Polignac number, because 642221137 - 2¹¹ = 642219089 is a prime.

It is not a weakly prime, because it can be changed into another prime (642221117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321110568 + 321110569.

It is an arithmetic number, because the mean of its divisors is an integer number (321110569).

Almost surely, 2^642221137 is an apocalyptic number.

It is an amenable number.

642221137 is a deficient number, since it is larger than the sum of its proper divisors (1).

642221137 is an equidigital number, since it uses as much as digits as its factorization.

642221137 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4032, while the sum is 28.

The square root of 642221137 is about 25342.0823335416. The cubic root of 642221137 is about 862.7696613091.

The spelling of 642221137 in words is "six hundred forty-two million, two hundred twenty-one thousand, one hundred thirty-seven".