997738981 has 2 divisors, whose sum is σ = 997738982. Its totient is φ = 997738980.

The previous prime is 997738979. The next prime is 997738991. The reversal of 997738981 is 189837799.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 571688100 + 426050881 = 23910^2 + 20641^2 .

It is a cyclic number.

It is not a de Polignac number, because 997738981 - 2¹ = 997738979 is a prime.

It is a super-2 number, since 2×997738981² = 1990966148413836722, which contains 22 as substring.

Together with 997738979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (997738901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 498869490 + 498869491.

It is an arithmetic number, because the mean of its divisors is an integer number (498869491).

Almost surely, 2^997738981 is an apocalyptic number.

It is an amenable number.

997738981 is a deficient number, since it is larger than the sum of its proper divisors (1).

997738981 is an equidigital number, since it uses as much as digits as its factorization.

997738981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6858432, while the sum is 61.

The square root of 997738981 is about 31587.0065216696. The cubic root of 997738981 is about 999.2457582624.

The spelling of 997738981 in words is "nine hundred ninety-seven million, seven hundred thirty-eight thousand, nine hundred eighty-one".