645189678169 has 3 divisors (see below), whose sum is σ = 645190481407. Its totient is φ = 645188874932.

The previous prime is 645189678149. The next prime is 645189678191. The reversal of 645189678169 is 961876981546.

It is a happy number.

The square root of 645189678169 is 803237.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 224263809225 + 420925868944 = 473565^2 + 648788^2 .

It is not a de Polignac number, because 645189678169 - 2⁷ = 645189678041 is a prime.

It is a super-2 number, since 2×645189678169² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 645189678098 and 645189678107.

It is not an unprimeable number, because it can be changed into a prime (645189678149) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 401619 + ... + 1204855.

Almost surely, 2^645189678169 is an apocalyptic number.

645189678169 is the 803237-th square number.

645189678169 is the 401619-th centered octagonal number.

It is an amenable number.

645189678169 is a deficient number, since it is larger than the sum of its proper divisors (803238).

645189678169 is an frugal number, since it uses more digits than its factorization.

645189678169 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1606474 (or 803237 counting only the distinct ones).

The product of its digits is 156764160, while the sum is 70.

The spelling of 645189678169 in words is "six hundred forty-five billion, one hundred eighty-nine million, six hundred seventy-eight thousand, one hundred sixty-nine".