99123781 has 4 divisors (see below), whose sum is σ = 99331200. Its totient is φ = 98916364.

The previous prime is 99123763. The next prime is 99123793. The reversal of 99123781 is 18732199.

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 99123781 - 2¹¹ = 99121733 is a prime.

It is a super-2 number, since 2×99123781² = 19651047919471922, 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 (99123751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 102991 + ... + 103948.

It is an arithmetic number, because the mean of its divisors is an integer number (24832800).

Almost surely, 2^99123781 is an apocalyptic number.

99123781 is the 4453-rd centered decagonal number.

It is an amenable number.

99123781 is a deficient number, since it is larger than the sum of its proper divisors (207419).

99123781 is a wasteful number, since it uses less digits than its factorization.

99123781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 207418.

The product of its digits is 27216, while the sum is 40.

The square root of 99123781 is about 9956.0926572627. The cubic root of 99123781 is about 462.7992216144.

The spelling of 99123781 in words is "ninety-nine million, one hundred twenty-three thousand, seven hundred eighty-one".