21771313 has 2 divisors, whose sum is σ = 21771314. Its totient is φ = 21771312.

The previous prime is 21771311. The next prime is 21771329. The reversal of 21771313 is 31317712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20007729 + 1763584 = 4473^2 + 1328^2 .

It is a cyclic number.

It is not a de Polignac number, because 21771313 - 2¹ = 21771311 is a prime.

It is a super-3 number, since 3×21771313³ (a number of 23 digits) contains 333 as substring.

Together with 21771311, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21771311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10885656 + 10885657.

It is an arithmetic number, because the mean of its divisors is an integer number (10885657).

Almost surely, 2^21771313 is an apocalyptic number.

It is an amenable number.

21771313 is a deficient number, since it is larger than the sum of its proper divisors (1).

21771313 is an equidigital number, since it uses as much as digits as its factorization.

21771313 is an evil number, because the sum of its binary digits is even.

The product of its digits is 882, while the sum is 25.

The square root of 21771313 is about 4665.9739604931. The cubic root of 21771313 is about 279.2296555077.

The spelling of 21771313 in words is "twenty-one million, seven hundred seventy-one thousand, three hundred thirteen".