642499191 has 24 divisors (see below), whose sum is σ = 963011504. Its totient is φ = 412439040.

The previous prime is 642499189. The next prime is 642499201. The reversal of 642499191 is 191994246.

It is not a de Polignac number, because 642499191 - 2¹ = 642499189 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 (642499171) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 22356 + ... + 42246.

Almost surely, 2^642499191 is an apocalyptic number.

642499191 is a deficient number, since it is larger than the sum of its proper divisors (320512313).

642499191 is a wasteful number, since it uses less digits than its factorization.

642499191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20031 (or 20028 counting only the distinct ones).

The product of its digits is 139968, while the sum is 45.

The square root of 642499191 is about 25347.5677531396. The cubic root of 642499191 is about 862.8941573371.

The spelling of 642499191 in words is "six hundred forty-two million, four hundred ninety-nine thousand, one hundred ninety-one".