21531310 has 16 divisors (see below), whose sum is σ = 38991456. Its totient is φ = 8560288.

The previous prime is 21531269. The next prime is 21531317. The reversal of 21531310 is 1313512.

It is a super-2 number, since 2×21531310² = 927194620632200, which contains 22 as substring.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531317) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 4777 + ... + 8116.

It is an arithmetic number, because the mean of its divisors is an integer number (2436966).

Almost surely, 2^21531310 is an apocalyptic number.

21531310 is a deficient number, since it is larger than the sum of its proper divisors (17460146).

21531310 is a wasteful number, since it uses less digits than its factorization.

21531310 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13067.

The product of its (nonzero) digits is 90, while the sum is 16.

The square root of 21531310 is about 4640.1842635826. The cubic root of 21531310 is about 278.1998028818.

Adding to 21531310 its reverse (1313512), we get a palindrome (22844822).

The spelling of 21531310 in words is "twenty-one million, five hundred thirty-one thousand, three hundred ten".