20475640 has 16 divisors (see below), whose sum is σ = 46070280. Its totient is φ = 8190240.

The previous prime is 20475613. The next prime is 20475641. The reversal of 20475640 is 4657402.

It is a junction number, because it is equal to n+sod(n) for n = 20475599 and 20475608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20475641) 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, 255906 + ... + 255985.

Almost surely, 2^20475640 is an apocalyptic number.

20475640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20475640 is an abundant number, since it is smaller than the sum of its proper divisors (25594640).

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

20475640 is a wasteful number, since it uses less digits than its factorization.

20475640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 511902 (or 511898 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 28.

The square root of 20475640 is about 4525.0016574583. The cubic root of 20475640 is about 273.5767347384.

It can be divided in two parts, 20475 and 640, that added together give a triangular number (21115 = T₂₀₅).

The spelling of 20475640 in words is "twenty million, four hundred seventy-five thousand, six hundred forty".