664873642 has 4 divisors (see below), whose sum is σ = 997310466. Its totient is φ = 332436820.

The previous prime is 664873637. The next prime is 664873663. The reversal of 664873642 is 246378466.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 246378466 = 2 ⋅123189233.

It can be written as a sum of positive squares in only one way, i.e., 574033681 + 90839961 = 23959^2 + 9531^2 .

It is a junction number, because it is equal to n+sod(n) for n = 664873592 and 664873601.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 166218409 + ... + 166218412.

Almost surely, 2^664873642 is an apocalyptic number.

664873642 is a deficient number, since it is larger than the sum of its proper divisors (332436824).

664873642 is a wasteful number, since it uses less digits than its factorization.

664873642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332436823.

The product of its digits is 1161216, while the sum is 46.

The square root of 664873642 is about 25785.1438235275. The cubic root of 664873642 is about 872.7965858979.

The spelling of 664873642 in words is "six hundred sixty-four million, eight hundred seventy-three thousand, six hundred forty-two".