641091664 has 10 divisors (see below), whose sum is σ = 1242115130. Its totient is φ = 320545824.

The previous prime is 641091631. The next prime is 641091667. The reversal of 641091664 is 466190146.

It can be written as a sum of positive squares in only one way, i.e., 600642064 + 40449600 = 24508^2 + 6360^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (641091667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20034099 + ... + 20034130.

It is an arithmetic number, because the mean of its divisors is an integer number (124211513).

Almost surely, 2^641091664 is an apocalyptic number.

It is an amenable number.

641091664 is a deficient number, since it is larger than the sum of its proper divisors (601023466).

641091664 is a wasteful number, since it uses less digits than its factorization.

641091664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40068237 (or 40068231 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 37.

The square root of 641091664 is about 25319.7879927933. The cubic root of 641091664 is about 862.2635807659.

The spelling of 641091664 in words is "six hundred forty-one million, ninety-one thousand, six hundred sixty-four".