20557440 has 192 divisors, whose sum is σ = 73513440. Its totient is φ = 5289984.

The previous prime is 20557421. The next prime is 20557447. The reversal of 20557440 is 4475502.

It is a tau number, because it is divible by the number of its divisors (192).

It is not an unprimeable number, because it can be changed into a prime (20557447) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 247639 + ... + 247721.

Almost surely, 2^20557440 is an apocalyptic number.

20557440 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 20557440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36756720).

20557440 is an abundant number, since it is smaller than the sum of its proper divisors (52956000).

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

20557440 is a wasteful number, since it uses less digits than its factorization.

20557440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151 (or 136 counting only the distinct ones).

The product of its (nonzero) digits is 5600, while the sum is 27.

The square root of 20557440 is about 4534.0313188155. The cubic root of 20557440 is about 273.9405628797.

The spelling of 20557440 in words is "twenty million, five hundred fifty-seven thousand, four hundred forty".