642256061 has 4 divisors (see below), whose sum is σ = 644643900. Its totient is φ = 639868224.

The previous prime is 642256019. The next prime is 642256151. The reversal of 642256061 is 160652246.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 160652246 = 2 ⋅80326123.

It can be written as a sum of positive squares in 2 ways, for example, as 228947161 + 413308900 = 15131^2 + 20330^2 .

It is a cyclic number.

It is not a de Polignac number, because 642256061 - 2⁶ = 642255997 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642256661) 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 in 3 ways as a sum of consecutive naturals, for example, 1193516 + ... + 1194053.

It is an arithmetic number, because the mean of its divisors is an integer number (161160975).

Almost surely, 2^642256061 is an apocalyptic number.

It is an amenable number.

642256061 is a deficient number, since it is larger than the sum of its proper divisors (2387839).

642256061 is a wasteful number, since it uses less digits than its factorization.

642256061 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2387838.

The product of its (nonzero) digits is 17280, while the sum is 32.

The square root of 642256061 is about 25342.7713756803. The cubic root of 642256061 is about 862.7853001702.

The spelling of 642256061 in words is "six hundred forty-two million, two hundred fifty-six thousand, sixty-one".