642245991 has 8 divisors (see below), whose sum is σ = 858797184. Its totient is φ = 426929400.

The previous prime is 642245969. The next prime is 642246019. The reversal of 642245991 is 199542246.

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

It is not a de Polignac number, because 642245991 - 2⁵ = 642245959 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642245911) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 307435 + ... + 309516.

It is an arithmetic number, because the mean of its divisors is an integer number (107349648).

Almost surely, 2^642245991 is an apocalyptic number.

642245991 is a deficient number, since it is larger than the sum of its proper divisors (216551193).

642245991 is a wasteful number, since it uses less digits than its factorization.

642245991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 617301.

The product of its digits is 155520, while the sum is 42.

The square root of 642245991 is about 25342.5726989191. The cubic root of 642245991 is about 862.7807909129.

The spelling of 642245991 in words is "six hundred forty-two million, two hundred forty-five thousand, nine hundred ninety-one".