644650453 has 4 divisors (see below), whose sum is σ = 659642368. Its totient is φ = 629658540.

The previous prime is 644650399. The next prime is 644650469. The reversal of 644650453 is 354056446.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 354056446 = 2 ⋅177028223.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644650453 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644651453) 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, 7495893 + ... + 7495978.

It is an arithmetic number, because the mean of its divisors is an integer number (164910592).

Almost surely, 2^644650453 is an apocalyptic number.

It is an amenable number.

644650453 is a deficient number, since it is larger than the sum of its proper divisors (14991915).

644650453 is a wasteful number, since it uses less digits than its factorization.

644650453 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14991914.

The product of its (nonzero) digits is 172800, while the sum is 37.

The square root of 644650453 is about 25389.9675659501. The cubic root of 644650453 is about 863.8561525532.

The spelling of 644650453 in words is "six hundred forty-four million, six hundred fifty thousand, four hundred fifty-three".