1640638164 has 96 divisors (see below), whose sum is σ = 4307821056. Its totient is φ = 481610880.

The previous prime is 1640638151. The next prime is 1640638171. The reversal of 1640638164 is 4618360461.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1381579 + ... + 1382765.

It is an arithmetic number, because the mean of its divisors is an integer number (44873136).

Almost surely, 2^1640638164 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1640638164, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2153910528).

1640638164 is an abundant number, since it is smaller than the sum of its proper divisors (2667182892).

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

1640638164 is a wasteful number, since it uses less digits than its factorization.

1640638164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1525 (or 1523 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 39.

The square root of 1640638164 is about 40504.7918646671. The cubic root of 1640638164 is about 1179.4266495455.

The spelling of 1640638164 in words is "one billion, six hundred forty million, six hundred thirty-eight thousand, one hundred sixty-four".