19641640 has 16 divisors (see below), whose sum is σ = 44193780. Its totient is φ = 7856640.

The previous prime is 19641623. The next prime is 19641679. The reversal of 19641640 is 4614691.

It can be written as a sum of positive squares in 2 ways, for example, as 15729156 + 3912484 = 3966^2 + 1978^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 245481 + ... + 245560.

Almost surely, 2^19641640 is an apocalyptic number.

19641640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19641640 is an abundant number, since it is smaller than the sum of its proper divisors (24552140).

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

19641640 is a wasteful number, since it uses less digits than its factorization.

19641640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 491052 (or 491048 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 19641640 is about 4431.8889877794. Note that the first 3 decimals coincide. The cubic root of 19641640 is about 269.8107498680.

The spelling of 19641640 in words is "nineteen million, six hundred forty-one thousand, six hundred forty".