2113211981 has 2 divisors, whose sum is σ = 2113211982. Its totient is φ = 2113211980.

The previous prime is 2113211941. The next prime is 2113212029. The reversal of 2113211981 is 1891123112.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1982475625 + 130736356 = 44525^2 + 11434^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2113211981 is a prime.

It is a super-2 number, since 2×2113211981² = 8931329753283888722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2113211941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1056605990 + 1056605991.

It is an arithmetic number, because the mean of its divisors is an integer number (1056605991).

Almost surely, 2^2113211981 is an apocalyptic number.

It is an amenable number.

2113211981 is a deficient number, since it is larger than the sum of its proper divisors (1).

2113211981 is an equidigital number, since it uses as much as digits as its factorization.

2113211981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 864, while the sum is 29.

The square root of 2113211981 is about 45969.6854568312. The cubic root of 2113211981 is about 1283.2591061958.

The spelling of 2113211981 in words is "two billion, one hundred thirteen million, two hundred eleven thousand, nine hundred eighty-one".