642731890 has 8 divisors (see below), whose sum is σ = 1156917420. Its totient is φ = 257092752.

The previous prime is 642731861. The next prime is 642731911. The reversal of 642731890 is 98137246.

It can be written as a sum of positive squares in 2 ways, for example, as 579894561 + 62837329 = 24081^2 + 7927^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 32136585 + ... + 32136604.

Almost surely, 2^642731890 is an apocalyptic number.

642731890 is a deficient number, since it is larger than the sum of its proper divisors (514185530).

642731890 is a wasteful number, since it uses less digits than its factorization.

642731890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64273196.

The product of its (nonzero) digits is 72576, while the sum is 40.

The square root of 642731890 is about 25352.1575018774. The cubic root of 642731890 is about 862.9983184910.

The spelling of 642731890 in words is "six hundred forty-two million, seven hundred thirty-one thousand, eight hundred ninety".