1543933981 has 2 divisors, whose sum is σ = 1543933982. Its totient is φ = 1543933980.

The previous prime is 1543933957. The next prime is 1543933991. The reversal of 1543933981 is 1893393451.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1161105625 + 382828356 = 34075^2 + 19566^2 .

It is an emirp because it is prime and its reverse (1893393451) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1543933981 - 2²⁹ = 1007063069 is a prime.

It is a super-2 number, since 2×1543933981² = 4767464275373016722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1543933991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 771966990 + 771966991.

It is an arithmetic number, because the mean of its divisors is an integer number (771966991).

Almost surely, 2^1543933981 is an apocalyptic number.

It is an amenable number.

1543933981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1543933981 is an equidigital number, since it uses as much as digits as its factorization.

1543933981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 349920, while the sum is 46.

The square root of 1543933981 is about 39292.9253301405. The cubic root of 1543933981 is about 1155.7828394116.

The spelling of 1543933981 in words is "one billion, five hundred forty-three million, nine hundred thirty-three thousand, nine hundred eighty-one".