21230691 has 16 divisors (see below), whose sum is σ = 29905920. Its totient is φ = 13376160.

The previous prime is 21230689. The next prime is 21230707. The reversal of 21230691 is 19603212.

It is not a de Polignac number, because 21230691 - 2¹ = 21230689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21230611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1345 + ... + 6653.

It is an arithmetic number, because the mean of its divisors is an integer number (1869120).

Almost surely, 2^21230691 is an apocalyptic number.

21230691 is a deficient number, since it is larger than the sum of its proper divisors (8675229).

21230691 is a wasteful number, since it uses less digits than its factorization.

21230691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5386.

The product of its (nonzero) digits is 648, while the sum is 24.

The square root of 21230691 is about 4607.6773975616. The cubic root of 21230691 is about 276.8989930919.

It can be divided in two parts, 212 and 30691, that added together give a palindrome (30903).

The spelling of 21230691 in words is "twenty-one million, two hundred thirty thousand, six hundred ninety-one".