645457 has 4 divisors (see below), whose sum is σ = 648036. Its totient is φ = 642880.

The previous prime is 645443. The next prime is 645467. The reversal of 645457 is 754546.

It is a happy number.

645457 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It can be written as a sum of positive squares in 2 ways, for example, as 370881 + 274576 = 609^2 + 524^2 .

It is a cyclic number.

It is not a de Polignac number, because 645457 - 2⁷ = 645329 is a prime.

It is a super-2 number, since 2×645457² = 833229477698, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645467) 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, 868 + ... + 1429.

It is an arithmetic number, because the mean of its divisors is an integer number (162009).

2⁶⁴⁵⁴⁵⁷ is an apocalyptic number.

It is an amenable number.

645457 is a deficient number, since it is larger than the sum of its proper divisors (2579).

645457 is a wasteful number, since it uses less digits than its factorization.

645457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2578.

The product of its digits is 16800, while the sum is 31.

The square root of 645457 is about 803.4033856040. The cubic root of 645457 is about 86.4216270306.

The spelling of 645457 in words is "six hundred forty-five thousand, four hundred fifty-seven".