642815387 has 2 divisors, whose sum is σ = 642815388. Its totient is φ = 642815386.

The previous prime is 642815351. The next prime is 642815399. The reversal of 642815387 is 783518246.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-642815387 is a prime.

It is not a weakly prime, because it can be changed into another prime (642815317) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321407693 + 321407694.

It is an arithmetic number, because the mean of its divisors is an integer number (321407694).

Almost surely, 2^642815387 is an apocalyptic number.

642815387 is a deficient number, since it is larger than the sum of its proper divisors (1).

642815387 is an equidigital number, since it uses as much as digits as its factorization.

642815387 is an evil number, because the sum of its binary digits is even.

The product of its digits is 322560, while the sum is 44.

The square root of 642815387 is about 25353.8041918762. The cubic root of 642815387 is about 863.0356874425.

The spelling of 642815387 in words is "six hundred forty-two million, eight hundred fifteen thousand, three hundred eighty-seven".