21780010 has 24 divisors (see below), whose sum is σ = 45605700. Its totient is φ = 7467264.

The previous prime is 21780007. The next prime is 21780037. The reversal of 21780010 is 1008712.

It can be written as a sum of positive squares in 2 ways, for example, as 21409129 + 370881 = 4627^2 + 609^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21780010.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 21735 + ... + 22714.

Almost surely, 2^21780010 is an apocalyptic number.

21780010 is an abundant number, since it is smaller than the sum of its proper divisors (23825690).

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

21780010 is a wasteful number, since it uses less digits than its factorization.

21780010 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44470 (or 44463 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 19.

The square root of 21780010 is about 4666.9058272050. The cubic root of 21780010 is about 279.2668319061.

Adding to 21780010 its reverse (1008712), we get a palindrome (22788722).

The spelling of 21780010 in words is "twenty-one million, seven hundred eighty thousand, ten".