1990185121 has 4 divisors (see below), whose sum is σ = 2107254852. Its totient is φ = 1873115392.

The previous prime is 1990185097. The next prime is 1990185137. The reversal of 1990185121 is 1215810991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1215810991 = 1217 ⋅999023.

It can be written as a sum of positive squares in 2 ways, for example, as 1066936896 + 923248225 = 32664^2 + 30385^2 .

It is a cyclic number.

It is not a de Polignac number, because 1990185121 - 2⁷ = 1990184993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1990185221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 58534840 + ... + 58534873.

It is an arithmetic number, because the mean of its divisors is an integer number (526813713).

Almost surely, 2^1990185121 is an apocalyptic number.

It is an amenable number.

1990185121 is a deficient number, since it is larger than the sum of its proper divisors (117069731).

1990185121 is a wasteful number, since it uses less digits than its factorization.

1990185121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117069730.

The product of its (nonzero) digits is 6480, while the sum is 37.

The square root of 1990185121 is about 44611.4909076126. The cubic root of 1990185121 is about 1257.8566738272.

The spelling of 1990185121 in words is "one billion, nine hundred ninety million, one hundred eighty-five thousand, one hundred twenty-one".