642710391 has 4 divisors (see below), whose sum is σ = 856947192. Its totient is φ = 428473592.

The previous prime is 642710377. The next prime is 642710407. The reversal of 642710391 is 193017246.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 642710391 - 2¹⁰ = 642709367 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642710291) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107118396 + ... + 107118401.

It is an arithmetic number, because the mean of its divisors is an integer number (214236798).

Almost surely, 2^642710391 is an apocalyptic number.

642710391 is a deficient number, since it is larger than the sum of its proper divisors (214236801).

642710391 is a wasteful number, since it uses less digits than its factorization.

642710391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214236800.

The product of its (nonzero) digits is 9072, while the sum is 33.

The square root of 642710391 is about 25351.7334910258. The cubic root of 642710391 is about 862.9886961233.

The spelling of 642710391 in words is "six hundred forty-two million, seven hundred ten thousand, three hundred ninety-one".