21303031 has 2 divisors, whose sum is σ = 21303032. Its totient is φ = 21303030.

The previous prime is 21303011. The next prime is 21303041. The reversal of 21303031 is 13030312.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21303031 is a prime.

It is a super-2 number, since 2×21303031² = 907638259573922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21303011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10651515 + 10651516.

It is an arithmetic number, because the mean of its divisors is an integer number (10651516).

Almost surely, 2^21303031 is an apocalyptic number.

21303031 is a deficient number, since it is larger than the sum of its proper divisors (1).

21303031 is an equidigital number, since it uses as much as digits as its factorization.

21303031 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 54, while the sum is 13.

The square root of 21303031 is about 4615.5206640205. The cubic root of 21303031 is about 277.2131321139.

Adding to 21303031 its reverse (13030312), we get a palindrome (34333343).

It can be divided in two parts, 2 and 1303031, that multiplied together give a palindrome (2606062).

The spelling of 21303031 in words is "twenty-one million, three hundred three thousand, thirty-one".