645400949 has 4 divisors (see below), whose sum is σ = 679369440. Its totient is φ = 611432460.

The previous prime is 645400933. The next prime is 645400961. The reversal of 645400949 is 949004546.

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.

It is a cyclic number.

It is not a de Polignac number, because 645400949 - 2⁴ = 645400933 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645400909) 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, 16984217 + ... + 16984254.

It is an arithmetic number, because the mean of its divisors is an integer number (169842360).

Almost surely, 2^645400949 is an apocalyptic number.

It is an amenable number.

645400949 is a deficient number, since it is larger than the sum of its proper divisors (33968491).

645400949 is a wasteful number, since it uses less digits than its factorization.

645400949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33968490.

The product of its (nonzero) digits is 155520, while the sum is 41.

The square root of 645400949 is about 25404.7426477813. The cubic root of 645400949 is about 864.1912536182.

The spelling of 645400949 in words is "six hundred forty-five million, four hundred thousand, nine hundred forty-nine".