21362531 has 4 divisors (see below), whose sum is σ = 22099200. Its totient is φ = 20625864.

The previous prime is 21362527. The next prime is 21362533. The reversal of 21362531 is 13526312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21362531 - 2² = 21362527 is a prime.

It is a super-2 number, since 2×21362531² = 912715461451922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21362497 and 21362506.

It is not an unprimeable number, because it can be changed into a prime (21362533) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 368291 + ... + 368348.

It is an arithmetic number, because the mean of its divisors is an integer number (5524800).

Almost surely, 2^21362531 is an apocalyptic number.

21362531 is a deficient number, since it is larger than the sum of its proper divisors (736669).

21362531 is an equidigital number, since it uses as much as digits as its factorization.

21362531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 736668.

The product of its digits is 1080, while the sum is 23.

The square root of 21362531 is about 4621.9618129102. The cubic root of 21362531 is about 277.4709803812.

Adding to 21362531 its reverse (13526312), we get a palindrome (34888843).

The spelling of 21362531 in words is "twenty-one million, three hundred sixty-two thousand, five hundred thirty-one".