645250553 has 4 divisors (see below), whose sum is σ = 651281040. Its totient is φ = 639220068.

The previous prime is 645250537. The next prime is 645250597. The reversal of 645250553 is 355052546.

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: 355052546 = 2 ⋅177526273.

It is a cyclic number.

It is not a de Polignac number, because 645250553 - 2⁴ = 645250537 is a prime.

It is a super-2 number, since 2×645250553² = 832696552293611618, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645258553) 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, 3015083 + ... + 3015296.

It is an arithmetic number, because the mean of its divisors is an integer number (162820260).

Almost surely, 2^645250553 is an apocalyptic number.

It is an amenable number.

645250553 is a deficient number, since it is larger than the sum of its proper divisors (6030487).

645250553 is a wasteful number, since it uses less digits than its factorization.

645250553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6030486.

The product of its (nonzero) digits is 90000, while the sum is 35.

The square root of 645250553 is about 25401.7824768263. The cubic root of 645250553 is about 864.1241217034.

The spelling of 645250553 in words is "six hundred forty-five million, two hundred fifty thousand, five hundred fifty-three".