21005110 has 16 divisors (see below), whose sum is σ = 43210656. Its totient is φ = 7201728.

The previous prime is 21005087. The next prime is 21005111. The reversal of 21005110 is 1150012.

It is a happy number.

It is a super-2 number, since 2×21005110² = 882429292224200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21005111) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 149967 + ... + 150106.

It is an arithmetic number, because the mean of its divisors is an integer number (2700666).

Almost surely, 2^21005110 is an apocalyptic number.

21005110 is an abundant number, since it is smaller than the sum of its proper divisors (22205546).

21005110 is a wasteful number, since it uses less digits than its factorization.

21005110 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 300087.

The product of its (nonzero) digits is 10, while the sum is 10.

The square root of 21005110 is about 4583.1332077521. The cubic root of 21005110 is about 275.9147937638.

Adding to 21005110 its reverse (1150012), we get a palindrome (22155122).

It can be divided in two parts, 21005 and 110, that added together give a triangular number (21115 = T₂₀₅).

The spelling of 21005110 in words is "twenty-one million, five thousand, one hundred ten".