642581377 has 2 divisors, whose sum is σ = 642581378. Its totient is φ = 642581376.

The previous prime is 642581363. The next prime is 642581399. The reversal of 642581377 is 773185246.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 374964496 + 267616881 = 19364^2 + 16359^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-642581377 is a prime.

It is a super-2 number, since 2×642581377² = 825821652134432258, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (642581077) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321290688 + 321290689.

It is an arithmetic number, because the mean of its divisors is an integer number (321290689).

Almost surely, 2^642581377 is an apocalyptic number.

It is an amenable number.

642581377 is a deficient number, since it is larger than the sum of its proper divisors (1).

642581377 is an equidigital number, since it uses as much as digits as its factorization.

642581377 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 282240, while the sum is 43.

The square root of 642581377 is about 25349.1888824870. The cubic root of 642581377 is about 862.9309484577.

The spelling of 642581377 in words is "six hundred forty-two million, five hundred eighty-one thousand, three hundred seventy-seven".