21711331 has 2 divisors, whose sum is σ = 21711332. Its totient is φ = 21711330.

The previous prime is 21711317. The next prime is 21711419. The reversal of 21711331 is 13311712.

21711331 = T₃₈₀₃ + T₃₈₀₄ + T₃₈₀₅.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21711331 is a prime.

It is a super-2 number, since 2×21711331² = 942763787583122, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21711299 and 21711308.

It is not a weakly prime, because it can be changed into another prime (21711301) 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, 10855665 + 10855666.

It is an arithmetic number, because the mean of its divisors is an integer number (10855666).

Almost surely, 2^21711331 is an apocalyptic number.

21711331 is the 3805-th centered triangular number.

21711331 is a deficient number, since it is larger than the sum of its proper divisors (1).

21711331 is an equidigital number, since it uses as much as digits as its factorization.

21711331 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 126, while the sum is 19.

The square root of 21711331 is about 4659.5419302760. The cubic root of 21711331 is about 278.9729850557.

The spelling of 21711331 in words is "twenty-one million, seven hundred eleven thousand, three hundred thirty-one".