20421780 has 48 divisors (see below), whose sum is σ = 58732800. Its totient is φ = 5298048.

The previous prime is 20421767. The next prime is 20421787. The reversal of 20421780 is 8712402.

It is a self number, because there is not a number n which added to its sum of digits gives 20421780.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20421787) by changing a digit.

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, 2380 + ... + 6819.

It is an arithmetic number, because the mean of its divisors is an integer number (1223600).

Almost surely, 2^20421780 is an apocalyptic number.

20421780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20421780 is an abundant number, since it is smaller than the sum of its proper divisors (38311020).

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

20421780 is a wasteful number, since it uses less digits than its factorization.

20421780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9248 (or 9246 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 24.

The square root of 20421780 is about 4519.0463595763. The cubic root of 20421780 is about 273.3366481190.

The spelling of 20421780 in words is "twenty million, four hundred twenty-one thousand, seven hundred eighty".