20520640 has 56 divisors (see below), whose sum is σ = 55851552. Its totient is φ = 7034880.

The previous prime is 20520629. The next prime is 20520653. The reversal of 20520640 is 4602502.

It is a tau number, because it is divible by the number of its divisors (56).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2341 + ... + 6820.

Almost surely, 2^20520640 is an apocalyptic number.

20520640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20520640 is an abundant number, since it is smaller than the sum of its proper divisors (35330912).

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

20520640 is an equidigital number, since it uses as much as digits as its factorization.

20520640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9185 (or 9175 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 19.

The square root of 20520640 is about 4529.9713023374. The cubic root of 20520640 is about 273.7770043487. Note that the first 3 decimals are identical.

The spelling of 20520640 in words is "twenty million, five hundred twenty thousand, six hundred forty".