644561662 has 8 divisors (see below), whose sum is σ = 1017729000. Its totient is φ = 305318664.

The previous prime is 644561587. The next prime is 644561663. The reversal of 644561662 is 266165446.

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

It is a super-2 number, since 2×644561662² = 830919472240404488, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644561663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8481037 + ... + 8481112.

It is an arithmetic number, because the mean of its divisors is an integer number (127216125).

Almost surely, 2^644561662 is an apocalyptic number.

644561662 is a deficient number, since it is larger than the sum of its proper divisors (373167338).

644561662 is a wasteful number, since it uses less digits than its factorization.

644561662 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16962170.

The product of its digits is 207360, while the sum is 40.

The square root of 644561662 is about 25388.2189607700. The cubic root of 644561662 is about 863.8164896252.

The spelling of 644561662 in words is "six hundred forty-four million, five hundred sixty-one thousand, six hundred sixty-two".