21431310 has 16 divisors (see below), whose sum is σ = 51435216. Its totient is φ = 5715008.

The previous prime is 21431309. The next prime is 21431317. The reversal of 21431310 is 1313412.

It is a super-2 number, since 2×21431310² = 918602096632200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21431310.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21431317) 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, 357159 + ... + 357218.

It is an arithmetic number, because the mean of its divisors is an integer number (3214701).

Almost surely, 2^21431310 is an apocalyptic number.

21431310 is an abundant number, since it is smaller than the sum of its proper divisors (30003906).

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

21431310 is a wasteful number, since it uses less digits than its factorization.

21431310 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 714387.

The product of its (nonzero) digits is 72, while the sum is 15.

The square root of 21431310 is about 4629.3962889344. The cubic root of 21431310 is about 277.7684440716.

Adding to 21431310 its reverse (1313412), we get a palindrome (22744722).

The spelling of 21431310 in words is "twenty-one million, four hundred thirty-one thousand, three hundred ten".