645221679 has 8 divisors (see below), whose sum is σ = 860670000. Its totient is φ = 429960576.

The previous prime is 645221617. The next prime is 645221683. The reversal of 645221679 is 976122546.

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

It is not a de Polignac number, because 645221679 - 2¹² = 645217583 is a prime.

It is a super-2 number, since 2×645221679² = 832622030103158082, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 645221679.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645228679) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 38554 + ... + 52695.

It is an arithmetic number, because the mean of its divisors is an integer number (107583750).

Almost surely, 2^645221679 is an apocalyptic number.

645221679 is a deficient number, since it is larger than the sum of its proper divisors (215448321).

645221679 is a wasteful number, since it uses less digits than its factorization.

645221679 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93609.

The product of its digits is 181440, while the sum is 42.

The square root of 645221679 is about 25401.2141245256. The cubic root of 645221679 is about 864.1112320892. Note that the first 3 decimals are identical.

The spelling of 645221679 in words is "six hundred forty-five million, two hundred twenty-one thousand, six hundred seventy-nine".