642665819 has 8 divisors (see below), whose sum is σ = 654501120. Its totient is φ = 630862056.

The previous prime is 642665791. The next prime is 642665851. The reversal of 642665819 is 918566246.

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 642665819 - 2²⁴ = 625888603 is a prime.

It is a super-2 number, since 2×642665819² = 826038709821881522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (642865819) 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, 35402 + ... + 50384.

It is an arithmetic number, because the mean of its divisors is an integer number (81812640).

Almost surely, 2^642665819 is an apocalyptic number.

642665819 is a deficient number, since it is larger than the sum of its proper divisors (11835301).

642665819 is a wasteful number, since it uses less digits than its factorization.

642665819 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15769.

The product of its digits is 622080, while the sum is 47.

The square root of 642665819 is about 25350.8544037474. The cubic root of 642665819 is about 862.9687462247.

The spelling of 642665819 in words is "six hundred forty-two million, six hundred sixty-five thousand, eight hundred nineteen".