21797131 has 2 divisors, whose sum is σ = 21797132. Its totient is φ = 21797130.

The previous prime is 21797129. The next prime is 21797159. The reversal of 21797131 is 13179712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21797131 - 2¹ = 21797129 is a prime.

It is a super-2 number, since 2×21797131² = 950229839662322, which contains 22 as substring.

Together with 21797129, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21797093 and 21797102.

It is not a weakly prime, because it can be changed into another prime (21777131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10898565 + 10898566.

It is an arithmetic number, because the mean of its divisors is an integer number (10898566).

Almost surely, 2^21797131 is an apocalyptic number.

21797131 is a deficient number, since it is larger than the sum of its proper divisors (1).

21797131 is an equidigital number, since it uses as much as digits as its factorization.

21797131 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2646, while the sum is 31.

The square root of 21797131 is about 4668.7397657184. The cubic root of 21797131 is about 279.3399888228.

The spelling of 21797131 in words is "twenty-one million, seven hundred ninety-seven thousand, one hundred thirty-one".