645799426 has 4 divisors (see below), whose sum is σ = 968699142. Its totient is φ = 322899712.

The previous prime is 645799403. The next prime is 645799433. The reversal of 645799426 is 624997546.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 624997546 = 2 ⋅312498773.

It can be written as a sum of positive squares in only one way, i.e., 592873801 + 52925625 = 24349^2 + 7275^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161449855 + ... + 161449858.

Almost surely, 2^645799426 is an apocalyptic number.

645799426 is a deficient number, since it is larger than the sum of its proper divisors (322899716).

645799426 is a wasteful number, since it uses less digits than its factorization.

645799426 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 322899715.

The product of its digits is 3265920, while the sum is 52.

The square root of 645799426 is about 25412.5840087151. The cubic root of 645799426 is about 864.3690704686.

The spelling of 645799426 in words is "six hundred forty-five million, seven hundred ninety-nine thousand, four hundred twenty-six".