1640432641 has 4 divisors (see below), whose sum is σ = 1641563092. Its totient is φ = 1639302192.

The previous prime is 1640432617. The next prime is 1640432653. The reversal of 1640432641 is 1462340461.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1462340461 = 2339 ⋅625199.

It can be written as a sum of positive squares in 2 ways, for example, as 1004636416 + 635796225 = 31696^2 + 25215^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1640432641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1640432041) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 563046 + ... + 565951.

It is an arithmetic number, because the mean of its divisors is an integer number (410390773).

Almost surely, 2^1640432641 is an apocalyptic number.

It is an amenable number.

1640432641 is a deficient number, since it is larger than the sum of its proper divisors (1130451).

1640432641 is a wasteful number, since it uses less digits than its factorization.

1640432641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1130450.

The product of its (nonzero) digits is 13824, while the sum is 31.

The square root of 1640432641 is about 40502.2547643955. The cubic root of 1640432641 is about 1179.3773985018.

It can be divided in two parts, 1640 and 432641, that added together give a square (434281 = 659²).

The spelling of 1640432641 in words is "one billion, six hundred forty million, four hundred thirty-two thousand, six hundred forty-one".