21093731 has 2 divisors, whose sum is σ = 21093732. Its totient is φ = 21093730.

The previous prime is 21093707. The next prime is 21093757. The reversal of 21093731 is 13739012.

It is an a-pointer prime, because the next prime (21093757) can be obtained adding 21093731 to its sum of digits (26).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21093731 - 2¹⁴ = 21077347 is a prime.

It is a super-2 number, since 2×21093731² = 889890975000722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21093731.

It is not a weakly prime, because it can be changed into another prime (21090731) 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 as a sum of consecutive naturals, namely, 10546865 + 10546866.

It is an arithmetic number, because the mean of its divisors is an integer number (10546866).

Almost surely, 2^21093731 is an apocalyptic number.

21093731 is a deficient number, since it is larger than the sum of its proper divisors (1).

21093731 is an equidigital number, since it uses as much as digits as its factorization.

21093731 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1134, while the sum is 26.

The square root of 21093731 is about 4592.7911992600. The cubic root of 21093731 is about 276.3022794391.

The spelling of 21093731 in words is "twenty-one million, ninety-three thousand, seven hundred thirty-one".