645415155221 has 4 divisors (see below), whose sum is σ = 656354395200. Its totient is φ = 634475915244.

The previous prime is 645415155193. The next prime is 645415155241. The reversal of 645415155221 is 122551514546.

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 645415155221 - 2⁶ = 645415155157 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 (645415155241) 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, 5469619901 + ... + 5469620018.

It is an arithmetic number, because the mean of its divisors is an integer number (164088598800).

Almost surely, 2^645415155221 is an apocalyptic number.

It is an amenable number.

645415155221 is a deficient number, since it is larger than the sum of its proper divisors (10939239979).

645415155221 is a wasteful number, since it uses less digits than its factorization.

645415155221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10939239978.

The product of its digits is 240000, while the sum is 41.

Adding to 645415155221 its reverse (122551514546), we get a palindrome (767966669767).

The spelling of 645415155221 in words is "six hundred forty-five billion, four hundred fifteen million, one hundred fifty-five thousand, two hundred twenty-one".