642001665 has 8 divisors (see below), whose sum is σ = 1027202688. Its totient is φ = 342400880.

The previous prime is 642001609. The next prime is 642001693. The reversal of 642001665 is 566100246.

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

It is not a de Polignac number, because 642001665 - 2⁶ = 642001601 is a prime.

It is a super-2 number, since 2×642001665² = 824332275725544450, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21400041 + ... + 21400070.

It is an arithmetic number, because the mean of its divisors is an integer number (128400336).

Almost surely, 2^642001665 is an apocalyptic number.

It is an amenable number.

642001665 is a deficient number, since it is larger than the sum of its proper divisors (385201023).

642001665 is a wasteful number, since it uses less digits than its factorization.

642001665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42800119.

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 642001665 is about 25337.7517747728. The cubic root of 642001665 is about 862.6713694352.

The spelling of 642001665 in words is "six hundred forty-two million, one thousand, six hundred sixty-five".