644614691 has 8 divisors (see below), whose sum is σ = 775476480. Its totient is φ = 523446408.

The previous prime is 644614681. The next prime is 644614693. The reversal of 644614691 is 196416446.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 644614691 - 2⁶ = 644614627 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644614693) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2423231 + ... + 2423496.

It is an arithmetic number, because the mean of its divisors is an integer number (96934560).

Almost surely, 2^644614691 is an apocalyptic number.

644614691 is a deficient number, since it is larger than the sum of its proper divisors (130861789).

644614691 is a wasteful number, since it uses less digits than its factorization.

644614691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4846753.

The product of its digits is 124416, while the sum is 41.

The square root of 644614691 is about 25389.2633016399. The cubic root of 644614691 is about 863.8401781106.

The spelling of 644614691 in words is "six hundred forty-four million, six hundred fourteen thousand, six hundred ninety-one".