2181394477 has 2 divisors, whose sum is σ = 2181394478. Its totient is φ = 2181394476.

The previous prime is 2181394447. The next prime is 2181394483. The reversal of 2181394477 is 7744931812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2169137476 + 12257001 = 46574^2 + 3501^2 .

It is a cyclic number.

It is not a de Polignac number, because 2181394477 - 2⁷ = 2181394349 is a prime.

It is a super-2 number, since 2×2181394477² = 9516963728572207058, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2181394447) 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, 1090697238 + 1090697239.

It is an arithmetic number, because the mean of its divisors is an integer number (1090697239).

Almost surely, 2^2181394477 is an apocalyptic number.

It is an amenable number.

2181394477 is a deficient number, since it is larger than the sum of its proper divisors (1).

2181394477 is an equidigital number, since it uses as much as digits as its factorization.

2181394477 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 338688, while the sum is 46.

The square root of 2181394477 is about 46705.4009403623. The cubic root of 2181394477 is about 1296.9146708623.

The spelling of 2181394477 in words is "two billion, one hundred eighty-one million, three hundred ninety-four thousand, four hundred seventy-seven".