644696897 has 8 divisors (see below), whose sum is σ = 696932544. Its totient is φ = 592838928.

The previous prime is 644696891. The next prime is 644696903. The reversal of 644696897 is 798696446.

It is an interprime number because it is at equal distance from previous prime (644696891) and next prime (644696903).

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 644696897 - 2¹⁰ = 644695873 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644696891) 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, 90863 + ... + 97700.

It is an arithmetic number, because the mean of its divisors is an integer number (87116568).

Almost surely, 2^644696897 is an apocalyptic number.

It is an amenable number.

644696897 is a deficient number, since it is larger than the sum of its proper divisors (52235647).

644696897 is a wasteful number, since it uses less digits than its factorization.

644696897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 188839.

The product of its digits is 15676416, while the sum is 59.

The square root of 644696897 is about 25390.8821626977. The cubic root of 644696897 is about 863.8768976312.

The spelling of 644696897 in words is "six hundred forty-four million, six hundred ninety-six thousand, eight hundred ninety-seven".