21116731 has 2 divisors, whose sum is σ = 21116732. Its totient is φ = 21116730.

The previous prime is 21116729. The next prime is 21116759. The reversal of 21116731 is 13761112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21116731 - 2¹ = 21116729 is a prime.

It is a super-2 number, since 2×21116731² = 891832656252722, which contains 22 as substring.

Together with 21116729, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21116701) 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, 10558365 + 10558366.

It is an arithmetic number, because the mean of its divisors is an integer number (10558366).

Almost surely, 2^21116731 is an apocalyptic number.

21116731 is a deficient number, since it is larger than the sum of its proper divisors (1).

21116731 is an equidigital number, since it uses as much as digits as its factorization.

21116731 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 252, while the sum is 22.

The square root of 21116731 is about 4595.2944410560. The cubic root of 21116731 is about 276.4026669914.

Adding to 21116731 its reverse (13761112), we get a palindrome (34877843).

The spelling of 21116731 in words is "twenty-one million, one hundred sixteen thousand, seven hundred thirty-one".