642981247 has 2 divisors, whose sum is σ = 642981248. Its totient is φ = 642981246.

The previous prime is 642981221. The next prime is 642981263. The reversal of 642981247 is 742189246.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-642981247 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642981347) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321490623 + 321490624.

It is an arithmetic number, because the mean of its divisors is an integer number (321490624).

Almost surely, 2^642981247 is an apocalyptic number.

642981247 is a deficient number, since it is larger than the sum of its proper divisors (1).

642981247 is an equidigital number, since it uses as much as digits as its factorization.

642981247 is an evil number, because the sum of its binary digits is even.

The product of its digits is 193536, while the sum is 43.

The square root of 642981247 is about 25357.0748904522. The cubic root of 642981247 is about 863.1099082284.

The spelling of 642981247 in words is "six hundred forty-two million, nine hundred eighty-one thousand, two hundred forty-seven".