1981607381 has 8 divisors (see below), whose sum is σ = 2207626680. Its totient is φ = 1766100672.

The previous prime is 1981607351. The next prime is 1981607417. The reversal of 1981607381 is 1837061891.

It can be written as a sum of positive squares in 4 ways, for example, as 378886225 + 1602721156 = 19465^2 + 40034^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1981607381 - 2¹⁰ = 1981606357 is a prime.

It is a super-2 number, since 2×1981607381² = 7853535624867358322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981607311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2627750 + ... + 2628503.

It is an arithmetic number, because the mean of its divisors is an integer number (275953335).

Almost surely, 2^1981607381 is an apocalyptic number.

It is an amenable number.

1981607381 is a deficient number, since it is larger than the sum of its proper divisors (226019299).

1981607381 is a wasteful number, since it uses less digits than its factorization.

1981607381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5256295.

The product of its (nonzero) digits is 72576, while the sum is 44.

The square root of 1981607381 is about 44515.2488592392. The cubic root of 1981607381 is about 1256.0469417068.

The spelling of 1981607381 in words is "one billion, nine hundred eighty-one million, six hundred seven thousand, three hundred eighty-one".