644001090 has 16 divisors (see below), whose sum is σ = 1545602688. Its totient is φ = 171733616.

The previous prime is 644001079. The next prime is 644001091. The reversal of 644001090 is 90100446.

It is a self number, because there is not a number n which added to its sum of digits gives 644001090.

It is not an unprimeable number, because it can be changed into a prime (644001091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10733322 + ... + 10733381.

It is an arithmetic number, because the mean of its divisors is an integer number (96600168).

Almost surely, 2^644001090 is an apocalyptic number.

644001090 is an abundant number, since it is smaller than the sum of its proper divisors (901601598).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644001090 is a wasteful number, since it uses less digits than its factorization.

644001090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21466713.

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 644001090 is about 25377.1765568985. The cubic root of 644001090 is about 863.5659980579.

The spelling of 644001090 in words is "six hundred forty-four million, one thousand, ninety".