21146831 has 2 divisors, whose sum is σ = 21146832. Its totient is φ = 21146830.

The previous prime is 21146813. The next prime is 21146833. The reversal of 21146831 is 13864112.

Together with previous prime (21146813) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21146831 is a prime.

It is a super-2 number, since 2×21146831² = 894376922685122, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 21146833, it forms a pair of twin primes.

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 21146831.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21146833) 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, 10573415 + 10573416.

It is an arithmetic number, because the mean of its divisors is an integer number (10573416).

Almost surely, 2^21146831 is an apocalyptic number.

21146831 is a deficient number, since it is larger than the sum of its proper divisors (1).

21146831 is an equidigital number, since it uses as much as digits as its factorization.

21146831 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1152, while the sum is 26.

The square root of 21146831 is about 4598.5683641760. The cubic root of 21146831 is about 276.5339336854.

The spelling of 21146831 in words is "twenty-one million, one hundred forty-six thousand, eight hundred thirty-one".