21050280 has 160 divisors (see below), whose sum is σ = 72527400. Its totient is φ = 5474304.

The previous prime is 21050279. The next prime is 21050287. The reversal of 21050280 is 8205012.

It can be written as a sum of positive squares in 4 ways, for example, as 14424804 + 6625476 = 3798^2 + 2574^2 .

It is a super-2 number, since 2×21050280² = 886228576156800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21050287) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 236476 + ... + 236564.

Almost surely, 2^21050280 is an apocalyptic number.

21050280 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 21050280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36263700).

21050280 is an abundant number, since it is smaller than the sum of its proper divisors (51477120).

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

21050280 is a wasteful number, since it uses less digits than its factorization.

21050280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 185 (or 172 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 21050280 is about 4588.0584128801. The cubic root of 21050280 is about 276.1124305649.

Adding to 21050280 its reverse (8205012), we get a palindrome (29255292).

The spelling of 21050280 in words is "twenty-one million, fifty thousand, two hundred eighty".