645619 has 4 divisors (see below), whose sum is σ = 695296. Its totient is φ = 595944.

The previous prime is 645611. The next prime is 645629. The reversal of 645619 is 916546.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 645619 - 2³ = 645611 is a prime.

It is a super-2 number, since 2×645619² = 833647786322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24819 + ... + 24844.

It is an arithmetic number, because the mean of its divisors is an integer number (173824).

2⁶⁴⁵⁶¹⁹ is an apocalyptic number.

645619 is a deficient number, since it is larger than the sum of its proper divisors (49677).

645619 is a wasteful number, since it uses less digits than its factorization.

645619 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49676.

The product of its digits is 6480, while the sum is 31.

The square root of 645619 is about 803.5042003624. The cubic root of 645619 is about 86.4288566020.

The spelling of 645619 in words is "six hundred forty-five thousand, six hundred nineteen".