642247651 has 2 divisors, whose sum is σ = 642247652. Its totient is φ = 642247650.

The previous prime is 642247637. The next prime is 642247679. The reversal of 642247651 is 156742246.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 642247651 - 2²¹ = 640150499 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 642247651.

It is not a weakly prime, because it can be changed into another prime (642247631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321123825 + 321123826.

It is an arithmetic number, because the mean of its divisors is an integer number (321123826).

Almost surely, 2^642247651 is an apocalyptic number.

642247651 is a deficient number, since it is larger than the sum of its proper divisors (1).

642247651 is an equidigital number, since it uses as much as digits as its factorization.

642247651 is an evil number, because the sum of its binary digits is even.

The product of its digits is 80640, while the sum is 37.

The square root of 642247651 is about 25342.6054501111. The cubic root of 642247651 is about 862.7815342495.

Adding to 642247651 its reverse (156742246), we get a palindrome (798989897).

The spelling of 642247651 in words is "six hundred forty-two million, two hundred forty-seven thousand, six hundred fifty-one".