20471640 has 64 divisors (see below), whose sum is σ = 70191360. Its totient is φ = 4679040.

The previous prime is 20471639. The next prime is 20471663. The reversal of 20471640 is 4617402.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 20471640.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11346 + ... + 13025.

It is an arithmetic number, because the mean of its divisors is an integer number (1096740).

Almost surely, 2^20471640 is an apocalyptic number.

20471640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20471640 is an abundant number, since it is smaller than the sum of its proper divisors (49719720).

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

20471640 is a wasteful number, since it uses less digits than its factorization.

20471640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24392 (or 24388 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 24.

The square root of 20471640 is about 4524.5596470817. The cubic root of 20471640 is about 273.5589188003.

The spelling of 20471640 in words is "twenty million, four hundred seventy-one thousand, six hundred forty".