1981331357 has 2 divisors, whose sum is σ = 1981331358. Its totient is φ = 1981331356.

The previous prime is 1981331353. The next prime is 1981331369. The reversal of 1981331357 is 7531331891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1118969401 + 862361956 = 33451^2 + 29366^2 .

It is a cyclic number.

It is not a de Polignac number, because 1981331357 - 2² = 1981331353 is a prime.

It is a super-3 number, since 3×1981331357³ (a number of 29 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1981331353) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 990665678 + 990665679.

It is an arithmetic number, because the mean of its divisors is an integer number (990665679).

Almost surely, 2^1981331357 is an apocalyptic number.

It is an amenable number.

1981331357 is a deficient number, since it is larger than the sum of its proper divisors (1).

1981331357 is an equidigital number, since it uses as much as digits as its factorization.

1981331357 is an evil number, because the sum of its binary digits is even.

The product of its digits is 68040, while the sum is 41.

The square root of 1981331357 is about 44512.1484204032. The cubic root of 1981331357 is about 1255.9886194910.

The spelling of 1981331357 in words is "one billion, nine hundred eighty-one million, three hundred thirty-one thousand, three hundred fifty-seven".