664563640 has 32 divisors (see below), whose sum is σ = 1610290080. Its totient is φ = 245377152.

The previous prime is 664563619. The next prime is 664563649. The reversal of 664563640 is 46365466.

It is a super-2 number, since 2×664563640² = 883289663220099200, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 664563593 and 664563602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664563649) 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, 638484 + ... + 639523.

It is an arithmetic number, because the mean of its divisors is an integer number (50321565).

Almost surely, 2^664563640 is an apocalyptic number.

It is an amenable number.

664563640 is an abundant number, since it is smaller than the sum of its proper divisors (945726440).

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

664563640 is a wasteful number, since it uses less digits than its factorization.

664563640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1278031 (or 1278027 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 40.

The square root of 664563640 is about 25779.1318705654. The cubic root of 664563640 is about 872.6609156329.

The spelling of 664563640 in words is "six hundred sixty-four million, five hundred sixty-three thousand, six hundred forty".