21778260 has 48 divisors (see below), whose sum is σ = 69691776. Its totient is φ = 4977792.

The previous prime is 21778259. The next prime is 21778261. The reversal of 21778260 is 6287712.

It is an interprime number because it is at equal distance from previous prime (21778259) and next prime (21778261).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21778261) 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, 25507 + ... + 26346.

It is an arithmetic number, because the mean of its divisors is an integer number (1451912).

Almost surely, 2^21778260 is an apocalyptic number.

21778260 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21778260 is an abundant number, since it is smaller than the sum of its proper divisors (47913516).

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

21778260 is a wasteful number, since it uses less digits than its factorization.

21778260 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51872 (or 51870 counting only the distinct ones).

The product of its (nonzero) digits is 9408, while the sum is 33.

The square root of 21778260 is about 4666.7183330473. The cubic root of 21778260 is about 279.2593521109.

The spelling of 21778260 in words is "twenty-one million, seven hundred seventy-eight thousand, two hundred sixty".