99978291 has 24 divisors (see below), whose sum is σ = 165794304. Its totient is φ = 56870640.

The previous prime is 99978251. The next prime is 99978293. The reversal of 99978291 is 19287999.

Added to its reverse (19287999) it gives a triangular number (119266290 = T₁₅₄₄₄).

It is not a de Polignac number, because 99978291 - 2⁶ = 99978227 is a prime.

It is not an unprimeable number, because it can be changed into a prime (99978293) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10806 + ... + 17796.

It is an arithmetic number, because the mean of its divisors is an integer number (6908096).

Almost surely, 2^99978291 is an apocalyptic number.

99978291 is a deficient number, since it is larger than the sum of its proper divisors (65816013).

99978291 is a wasteful number, since it uses less digits than its factorization.

99978291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7231 (or 7228 counting only the distinct ones).

The product of its digits is 734832, while the sum is 54.

The square root of 99978291 is about 9998.9144910835. The cubic root of 99978291 is about 464.1252928464.

Adding to 99978291 its reverse (19287999), we get a triangular number (119266290 = T₁₅₄₄₄).

The spelling of 99978291 in words is "ninety-nine million, nine hundred seventy-eight thousand, two hundred ninety-one".