644536897 has 8 divisors (see below), whose sum is σ = 659172096. Its totient is φ = 629940192.

The previous prime is 644536891. The next prime is 644536969. The reversal of 644536897 is 798635446.

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 644536897 - 2¹⁹ = 644012609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644536891) 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, 25693 + ... + 44149.

It is an arithmetic number, because the mean of its divisors is an integer number (82396512).

Almost surely, 2^644536897 is an apocalyptic number.

It is an amenable number.

644536897 is a deficient number, since it is larger than the sum of its proper divisors (14635199).

644536897 is a wasteful number, since it uses less digits than its factorization.

644536897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19247.

The product of its digits is 4354560, while the sum is 52.

The square root of 644536897 is about 25387.7312298677. The cubic root of 644536897 is about 863.8054264534.

The spelling of 644536897 in words is "six hundred forty-four million, five hundred thirty-six thousand, eight hundred ninety-seven".