20478640 has 160 divisors (see below), whose sum is σ = 61246080. Its totient is φ = 6193152.

The previous prime is 20478629. The next prime is 20478641. The reversal of 20478640 is 4687402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20478641) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 211072 + ... + 211168.

It is an arithmetic number, because the mean of its divisors is an integer number (382788).

Almost surely, 2^20478640 is an apocalyptic number.

20478640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20478640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30623040).

20478640 is an abundant number, since it is smaller than the sum of its proper divisors (40767440).

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

20478640 is a wasteful number, since it uses less digits than its factorization.

20478640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159 (or 153 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 31.

The square root of 20478640 is about 4525.3331369083. Note that the first 3 decimals coincide. The cubic root of 20478640 is about 273.5900951694.

The spelling of 20478640 in words is "twenty million, four hundred seventy-eight thousand, six hundred forty".