20421280 has 96 divisors (see below), whose sum is σ = 54105408. Its totient is φ = 7219200.

The previous prime is 20421277. The next prime is 20421287. The reversal of 20421280 is 8212402.

It is not an unprimeable number, because it can be changed into a prime (20421287) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 72019 + ... + 72301.

It is an arithmetic number, because the mean of its divisors is an integer number (563598).

Almost surely, 2^20421280 is an apocalyptic number.

20421280 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 20421280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27052704).

20421280 is an abundant number, since it is smaller than the sum of its proper divisors (33684128).

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

20421280 is a wasteful number, since it uses less digits than its factorization.

20421280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 350 (or 342 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 19.

The square root of 20421280 is about 4518.9910378313. The cubic root of 20421280 is about 273.3344173399.

Adding to 20421280 its reverse (8212402), we get a palindrome (28633682).

The spelling of 20421280 in words is "twenty million, four hundred twenty-one thousand, two hundred eighty".