21021130 has 32 divisors (see below), whose sum is σ = 41177808. Its totient is φ = 7680000.

The previous prime is 21021127. The next prime is 21021157. The reversal of 21021130 is 3112012.

It can be written as a sum of positive squares in 8 ways, for example, as 17969121 + 3052009 = 4239^2 + 1747^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12330 + ... + 13930.

Almost surely, 2^21021130 is an apocalyptic number.

21021130 is a deficient number, since it is larger than the sum of its proper divisors (20156678).

21021130 is a wasteful number, since it uses less digits than its factorization.

21021130 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1722.

The product of its (nonzero) digits is 12, while the sum is 10.

The square root of 21021130 is about 4584.8805873218. The cubic root of 21021130 is about 275.9849200611.

Adding to 21021130 its reverse (3112012), we get a palindrome (24133142).

The spelling of 21021130 in words is "twenty-one million, twenty-one thousand, one hundred thirty".