6543137981 has 2 divisors, whose sum is σ = 6543137982. Its totient is φ = 6543137980.

The previous prime is 6543137959. The next prime is 6543137987. The reversal of 6543137981 is 1897313456.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4348215481 + 2194922500 = 65941^2 + 46850^2 .

It is a cyclic number.

It is not a de Polignac number, because 6543137981 - 2¹⁴ = 6543121597 is a prime.

It is a super-2 number, since 2×6543137981² = 85625309276809512722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6543137987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3271568990 + 3271568991.

It is an arithmetic number, because the mean of its divisors is an integer number (3271568991).

Almost surely, 2^6543137981 is an apocalyptic number.

It is an amenable number.

6543137981 is a deficient number, since it is larger than the sum of its proper divisors (1).

6543137981 is an equidigital number, since it uses as much as digits as its factorization.

6543137981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 544320, while the sum is 47.

The square root of 6543137981 is about 80889.6654771177. The cubic root of 6543137981 is about 1870.3750171074.

The spelling of 6543137981 in words is "six billion, five hundred forty-three million, one hundred thirty-seven thousand, nine hundred eighty-one".