99789921 has 48 divisors (see below), whose sum is σ = 187634880. Its totient is φ = 51831360.

The previous prime is 99789901. The next prime is 99789931. The reversal of 99789921 is 12998799.

99789921 = 1403² + 1404² + ... + 1451².

It is not a de Polignac number, because 99789921 - 2⁶ = 99789857 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (99789901) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 11125 + ... + 17981.

It is an arithmetic number, because the mean of its divisors is an integer number (3909060).

Almost surely, 2^99789921 is an apocalyptic number.

It is an amenable number.

99789921 is a deficient number, since it is larger than the sum of its proper divisors (87844959).

99789921 is a wasteful number, since it uses less digits than its factorization.

99789921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6891 (or 6878 counting only the distinct ones).

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

The square root of 99789921 is about 9989.4905275494. The cubic root of 99789921 is about 463.8336220394.

The spelling of 99789921 in words is "ninety-nine million, seven hundred eighty-nine thousand, nine hundred twenty-one".