21781050 has 24 divisors (see below), whose sum is σ = 54017376. Its totient is φ = 5808240.

The previous prime is 21781021. The next prime is 21781093. The reversal of 21781050 is 5018712.

It is a self number, because there is not a number n which added to its sum of digits gives 21781050.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 72454 + ... + 72753.

It is an arithmetic number, because the mean of its divisors is an integer number (2250724).

Almost surely, 2^21781050 is an apocalyptic number.

21781050 is an abundant number, since it is smaller than the sum of its proper divisors (32236326).

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

21781050 is a wasteful number, since it uses less digits than its factorization.

21781050 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145222 (or 145217 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 24.

The square root of 21781050 is about 4667.0172487361. The cubic root of 21781050 is about 279.2712768518.

Adding to 21781050 its reverse (5018712), we get a palindrome (26799762).

The spelling of 21781050 in words is "twenty-one million, seven hundred eighty-one thousand, fifty".