645249137 has 4 divisors (see below), whose sum is σ = 694883700. Its totient is φ = 595614576.

The previous prime is 645249133. The next prime is 645249167. The reversal of 645249137 is 731942546.

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 178516321 + 466732816 = 13361^2 + 21604^2 .

It is a cyclic number.

It is not a de Polignac number, because 645249137 - 2² = 645249133 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 645249094 and 645249103.

It is not an unprimeable number, because it can be changed into a prime (645249133) 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, 24817262 + ... + 24817287.

It is an arithmetic number, because the mean of its divisors is an integer number (173720925).

Almost surely, 2^645249137 is an apocalyptic number.

It is an amenable number.

645249137 is a deficient number, since it is larger than the sum of its proper divisors (49634563).

645249137 is a wasteful number, since it uses less digits than its factorization.

645249137 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49634562.

The product of its digits is 181440, while the sum is 41.

The square root of 645249137 is about 25401.7546047512. The cubic root of 645249137 is about 864.1234895972.

The spelling of 645249137 in words is "six hundred forty-five million, two hundred forty-nine thousand, one hundred thirty-seven".