21005310 has 32 divisors (see below), whose sum is σ = 51056640. Its totient is φ = 5529888.

The previous prime is 21005297. The next prime is 21005311. The reversal of 21005310 is 1350012.

It is a super-2 number, since 2×21005310² = 882446096392200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21005311) 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, 2062 + ... + 6801.

It is an arithmetic number, because the mean of its divisors is an integer number (1595520).

Almost surely, 2^21005310 is an apocalyptic number.

21005310 is an abundant number, since it is smaller than the sum of its proper divisors (30051330).

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

21005310 is a wasteful number, since it uses less digits than its factorization.

21005310 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8952.

The product of its (nonzero) digits is 30, while the sum is 12.

The square root of 21005310 is about 4583.1550268347. The cubic root of 21005310 is about 275.9156694679.

Adding to 21005310 its reverse (1350012), we get a palindrome (22355322).

The spelling of 21005310 in words is "twenty-one million, five thousand, three hundred ten".