991430121 has 16 divisors (see below), whose sum is σ = 1442612160. Its totient is φ = 600645120.

The previous prime is 991430119. The next prime is 991430147. The reversal of 991430121 is 121034199.

It is not a de Polignac number, because 991430121 - 2¹ = 991430119 is a prime.

It is not an unprimeable number, because it can be changed into a prime (991430821) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 152881 + ... + 159233.

It is an arithmetic number, because the mean of its divisors is an integer number (90163260).

Almost surely, 2^991430121 is an apocalyptic number.

It is an amenable number.

991430121 is a deficient number, since it is larger than the sum of its proper divisors (451182039).

991430121 is a wasteful number, since it uses less digits than its factorization.

991430121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11096.

The product of its (nonzero) digits is 1944, while the sum is 30.

The square root of 991430121 is about 31486.9833582069. The cubic root of 991430121 is about 997.1351742777.

The spelling of 991430121 in words is "nine hundred ninety-one million, four hundred thirty thousand, one hundred twenty-one".