999872121 has 32 divisors (see below), whose sum is σ = 1397658240. Its totient is φ = 635027456.

The previous prime is 999872059. The next prime is 999872129. The reversal of 999872121 is 121278999.

999872121 is a nontrivial binomial coefficient, being equal to C(44719, 2).

It is a cyclic number.

It is not a de Polignac number, because 999872121 - 2⁶ = 999872057 is a prime.

It is not an unprimeable number, because it can be changed into a prime (999872129) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3890425 + ... + 3890681.

It is an arithmetic number, because the mean of its divisors is an integer number (43676820).

Almost surely, 2^999872121 is an apocalyptic number.

999872121 is the 44718-th triangular number.

It is an amenable number.

999872121 is a deficient number, since it is larger than the sum of its proper divisors (397786119).

999872121 is a wasteful number, since it uses less digits than its factorization.

999872121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 713.

The product of its digits is 163296, while the sum is 48.

The square root of 999872121 is about 31620.7545925141. The cubic root of 999872121 is about 999.9573718495.

The spelling of 999872121 in words is "nine hundred ninety-nine million, eight hundred seventy-two thousand, one hundred twenty-one".