99991993 has 8 divisors (see below), whose sum is σ = 101911880. Its totient is φ = 98081280.

The previous prime is 99991987. The next prime is 99991999. The reversal of 99991993 is 39919999.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (99991987) and next prime (99991999).

It can be written as a sum of positive squares in 4 ways, for example, as 4108729 + 95883264 = 2027^2 + 9792^2 .

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 99991993 - 2⁹ = 99991481 is a prime.

It is a super-2 number, since 2×99991993² = 19996797328224098, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (99991999) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22153 + ... + 26281.

It is an arithmetic number, because the mean of its divisors is an integer number (12738985).

Almost surely, 2^99991993 is an apocalyptic number.

It is an amenable number.

99991993 is a deficient number, since it is larger than the sum of its proper divisors (1919887).

99991993 is a wasteful number, since it uses less digits than its factorization.

99991993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4587.

The product of its digits is 1594323, while the sum is 58.

The square root of 99991993 is about 9999.5996419857. The cubic root of 99991993 is about 464.1464946300.

The spelling of 99991993 in words is "ninety-nine million, nine hundred ninety-one thousand, nine hundred ninety-three".