642318421 has 2 divisors, whose sum is σ = 642318422. Its totient is φ = 642318420.

The previous prime is 642318343. The next prime is 642318433. The reversal of 642318421 is 124813246.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 593458321 + 48860100 = 24361^2 + 6990^2 .

It is a cyclic number.

It is not a de Polignac number, because 642318421 - 2¹⁷ = 642187349 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642318461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321159210 + 321159211.

It is an arithmetic number, because the mean of its divisors is an integer number (321159211).

Almost surely, 2^642318421 is an apocalyptic number.

It is an amenable number.

642318421 is a deficient number, since it is larger than the sum of its proper divisors (1).

642318421 is an equidigital number, since it uses as much as digits as its factorization.

642318421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9216, while the sum is 31.

The square root of 642318421 is about 25344.0016769254. The cubic root of 642318421 is about 862.8132233789.

The spelling of 642318421 in words is "six hundred forty-two million, three hundred eighteen thousand, four hundred twenty-one".