642881 has 2 divisors, whose sum is σ = 642882. Its totient is φ = 642880.

The previous prime is 642877. The next prime is 642899. The reversal of 642881 is 188246.

642881 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 490000 + 152881 = 700^2 + 391^2 .

It is a cyclic number.

It is not a de Polignac number, because 642881 - 2² = 642877 is a prime.

It is a super-2 number, since 2×642881² = 826591960322, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (642871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321440 + 321441.

It is an arithmetic number, because the mean of its divisors is an integer number (321441).

2⁶⁴²⁸⁸¹ is an apocalyptic number.

It is an amenable number.

642881 is a deficient number, since it is larger than the sum of its proper divisors (1).

642881 is an equidigital number, since it uses as much as digits as its factorization.

642881 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3072, while the sum is 29.

The square root of 642881 is about 801.7986031417. The cubic root of 642881 is about 86.3065050167.

The spelling of 642881 in words is "six hundred forty-two thousand, eight hundred eighty-one".