20645280 has 192 divisors, whose sum is σ = 74390400. Its totient is φ = 5412096.

The previous prime is 20645269. The next prime is 20645281. The reversal of 20645280 is 8254602.

20645280 is a `hidden beast` number, since 206 + 452 + 8 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20645281) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 349891 + ... + 349949.

It is an arithmetic number, because the mean of its divisors is an integer number (387450).

Almost surely, 2^20645280 is an apocalyptic number.

20645280 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 20645280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37195200).

20645280 is an abundant number, since it is smaller than the sum of its proper divisors (53745120).

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

20645280 is an frugal number, since it uses more digits than its factorization.

20645280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95 (or 69 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The square root of 20645280 is about 4543.7077370799. The cubic root of 20645280 is about 274.3301825224.

Adding to 20645280 its reverse (8254602), we get a palindrome (28899882).

The spelling of 20645280 in words is "twenty million, six hundred forty-five thousand, two hundred eighty".