642640305 has 8 divisors (see below), whose sum is σ = 1028224512. Its totient is φ = 342741488.

The previous prime is 642640303. The next prime is 642640333. The reversal of 642640305 is 503046246.

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

It is a cyclic number.

It is not a de Polignac number, because 642640305 - 2¹ = 642640303 is a prime.

It is a super-2 number, since 2×642640305² = 825973123220986050, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (642640301) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21421329 + ... + 21421358.

It is an arithmetic number, because the mean of its divisors is an integer number (128528064).

Almost surely, 2^642640305 is an apocalyptic number.

It is an amenable number.

642640305 is a deficient number, since it is larger than the sum of its proper divisors (385584207).

642640305 is a wasteful number, since it uses less digits than its factorization.

642640305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42842695.

The product of its (nonzero) digits is 17280, while the sum is 30.

The square root of 642640305 is about 25350.3511809994. The cubic root of 642640305 is about 862.9573260458.

The spelling of 642640305 in words is "six hundred forty-two million, six hundred forty thousand, three hundred five".