21242631 has 8 divisors (see below), whose sum is σ = 28350720. Its totient is φ = 14148152.

The previous prime is 21242629. The next prime is 21242651. The reversal of 21242631 is 13624212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21242631 - 2¹ = 21242629 is a prime.

It is a super-3 number, since 3×21242631³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a junction number, because it is equal to n+sod(n) for n = 21242598 and 21242607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21242651) 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, 1090 + ... + 6608.

It is an arithmetic number, because the mean of its divisors is an integer number (3543840).

Almost surely, 2^21242631 is an apocalyptic number.

21242631 is a deficient number, since it is larger than the sum of its proper divisors (7108089).

21242631 is a wasteful number, since it uses less digits than its factorization.

21242631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6805.

The product of its digits is 576, while the sum is 21.

The square root of 21242631 is about 4608.9728790697. The cubic root of 21242631 is about 276.9508920838.

Adding to 21242631 its reverse (13624212), we get a palindrome (34866843).

The spelling of 21242631 in words is "twenty-one million, two hundred forty-two thousand, six hundred thirty-one".