645473765 has 8 divisors (see below), whose sum is σ = 820131480. Its totient is φ = 486003712.

The previous prime is 645473749. The next prime is 645473767. The reversal of 645473765 is 567374546.

It can be written as a sum of positive squares in 4 ways, for example, as 22572001 + 622901764 = 4751^2 + 24958^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 645473765 - 2⁴ = 645473749 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645473767) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3796820 + ... + 3796989.

It is an arithmetic number, because the mean of its divisors is an integer number (102516435).

Almost surely, 2^645473765 is an apocalyptic number.

It is an amenable number.

645473765 is a deficient number, since it is larger than the sum of its proper divisors (174657715).

645473765 is a wasteful number, since it uses less digits than its factorization.

645473765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7593831.

The product of its digits is 2116800, while the sum is 47.

The square root of 645473765 is about 25406.1757255987. The cubic root of 645473765 is about 864.2237525808.

The spelling of 645473765 in words is "six hundred forty-five million, four hundred seventy-three thousand, seven hundred sixty-five".