6433981 has 2 divisors, whose sum is σ = 6433982. Its totient is φ = 6433980.

The previous prime is 6433963. The next prime is 6433991. The reversal of 6433981 is 1893346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5331481 + 1102500 = 2309^2 + 1050^2 .

It is a cyclic number.

It is not a de Polignac number, because 6433981 - 2¹³ = 6425789 is a prime.

It is a super-2 number, since 2×6433981² = 82792223016722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6433991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3216990 + 3216991.

It is an arithmetic number, because the mean of its divisors is an integer number (3216991).

Almost surely, 2^6433981 is an apocalyptic number.

It is an amenable number.

6433981 is a deficient number, since it is larger than the sum of its proper divisors (1).

6433981 is an equidigital number, since it uses as much as digits as its factorization.

6433981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552, while the sum is 34.

The square root of 6433981 is about 2536.5293217308. The cubic root of 6433981 is about 185.9915689708.

It can be divided in two parts, 643 and 3981, that added together give a square (4624 = 68²).

The spelling of 6433981 in words is "six million, four hundred thirty-three thousand, nine hundred eighty-one".