6211981 has 2 divisors, whose sum is σ = 6211982. Its totient is φ = 6211980.

The previous prime is 6211973. The next prime is 6212009. The reversal of 6211981 is 1891126.

It is a happy number.

It is an a-pointer prime, because the next prime (6212009) can be obtained adding 6211981 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6200100 + 11881 = 2490^2 + 109^2 .

It is a cyclic number.

It is not a de Polignac number, because 6211981 - 2³ = 6211973 is a prime.

It is a super-2 number, since 2×6211981² = 77177415888722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6211901) 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, 3105990 + 3105991.

It is an arithmetic number, because the mean of its divisors is an integer number (3105991).

Almost surely, 2^6211981 is an apocalyptic number.

It is an amenable number.

6211981 is a deficient number, since it is larger than the sum of its proper divisors (1).

6211981 is an equidigital number, since it uses as much as digits as its factorization.

6211981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 864, while the sum is 28.

The square root of 6211981 is about 2492.3846011400. The cubic root of 6211981 is about 183.8273131705.

The spelling of 6211981 in words is "six million, two hundred eleven thousand, nine hundred eighty-one".