642052261 has 2 divisors, whose sum is σ = 642052262. Its totient is φ = 642052260.

The previous prime is 642052217. The next prime is 642052283. The reversal of 642052261 is 162250246.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 505980036 + 136072225 = 22494^2 + 11665^2 .

It is a cyclic number.

It is not a de Polignac number, because 642052261 - 2²¹ = 639955109 is a prime.

It is a super-4 number, since 4×642052261⁴ (a number of 36 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642052211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321026130 + 321026131.

It is an arithmetic number, because the mean of its divisors is an integer number (321026131).

Almost surely, 2^642052261 is an apocalyptic number.

It is an amenable number.

642052261 is a deficient number, since it is larger than the sum of its proper divisors (1).

642052261 is an equidigital number, since it uses as much as digits as its factorization.

642052261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5760, while the sum is 28.

The square root of 642052261 is about 25338.7501862266. The cubic root of 642052261 is about 862.6940311490.

It can be divided in two parts, 64205 and 2261, that added together give a palindrome (66466).

The spelling of 642052261 in words is "six hundred forty-two million, fifty-two thousand, two hundred sixty-one".