93991981 has 4 divisors (see below), whose sum is σ = 94082464. Its totient is φ = 93901500.

The previous prime is 93991957. The next prime is 93991999. The reversal of 93991981 is 18919939.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 93991981 - 2¹¹ = 93989933 is a prime.

It is a super-2 number, since 2×93991981² = 17668984984608722, 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 (93991901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43665 + ... + 45766.

It is an arithmetic number, because the mean of its divisors is an integer number (23520616).

Almost surely, 2^93991981 is an apocalyptic number.

It is an amenable number.

93991981 is a deficient number, since it is larger than the sum of its proper divisors (90483).

93991981 is a wasteful number, since it uses less digits than its factorization.

93991981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90482.

The product of its digits is 157464, while the sum is 49.

The square root of 93991981 is about 9694.9461576638. The cubic root of 93991981 is about 454.6706645499.

The spelling of 93991981 in words is "ninety-three million, nine hundred ninety-one thousand, nine hundred eighty-one".