1641690121 has 4 divisors (see below), whose sum is σ = 1645236352. Its totient is φ = 1638143892.

The previous prime is 1641690059. The next prime is 1641690137. The reversal of 1641690121 is 1210961461.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1641690121 - 2²³ = 1633301513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1641690191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1772421 + ... + 1773346.

It is an arithmetic number, because the mean of its divisors is an integer number (411309088).

Almost surely, 2^1641690121 is an apocalyptic number.

It is an amenable number.

1641690121 is a deficient number, since it is larger than the sum of its proper divisors (3546231).

1641690121 is an equidigital number, since it uses as much as digits as its factorization.

1641690121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3546230.

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 1641690121 is about 40517.7753708172. The cubic root of 1641690121 is about 1179.6786736393.

The spelling of 1641690121 in words is "one billion, six hundred forty-one million, six hundred ninety thousand, one hundred twenty-one".