642905099 has 4 divisors (see below), whose sum is σ = 680723064. Its totient is φ = 605087136.

The previous prime is 642905069. The next prime is 642905119. The reversal of 642905099 is 990509246.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 990509246 = 2 ⋅495254623.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-642905099 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (642905009) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18908957 + ... + 18908990.

It is an arithmetic number, because the mean of its divisors is an integer number (170180766).

Almost surely, 2^642905099 is an apocalyptic number.

642905099 is a deficient number, since it is larger than the sum of its proper divisors (37817965).

642905099 is a wasteful number, since it uses less digits than its factorization.

642905099 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37817964.

The product of its (nonzero) digits is 174960, while the sum is 44.

The square root of 642905099 is about 25355.5733321098. The cubic root of 642905099 is about 863.0758343015.

The spelling of 642905099 in words is "six hundred forty-two million, nine hundred five thousand, ninety-nine".