642681493 has 4 divisors (see below), whose sum is σ = 642744160. Its totient is φ = 642618828.

The previous prime is 642681469. The next prime is 642681509. The reversal of 642681493 is 394186246.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 642681493 - 2⁵ = 642681461 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642681443) 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, 11955 + ... + 37792.

It is an arithmetic number, because the mean of its divisors is an integer number (160686040).

Almost surely, 2^642681493 is an apocalyptic number.

It is an amenable number.

642681493 is a deficient number, since it is larger than the sum of its proper divisors (62667).

642681493 is a wasteful number, since it uses less digits than its factorization.

642681493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62666.

The product of its digits is 248832, while the sum is 43.

The square root of 642681493 is about 25351.1635433169. The cubic root of 642681493 is about 862.9757618264.

The spelling of 642681493 in words is "six hundred forty-two million, six hundred eighty-one thousand, four hundred ninety-three".