20291990123 has 4 divisors (see below), whose sum is σ = 20478155280. Its totient is φ = 20105824968.

The previous prime is 20291990119. The next prime is 20291990203. The reversal of 20291990123 is 32109919202.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 32109919202 = 2 ⋅16054959601.

It is a cyclic number.

It is not a de Polignac number, because 20291990123 - 2² = 20291990119 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20291990423) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 93082415 + ... + 93082632.

It is an arithmetic number, because the mean of its divisors is an integer number (5119538820).

Almost surely, 2^20291990123 is an apocalyptic number.

20291990123 is a deficient number, since it is larger than the sum of its proper divisors (186165157).

20291990123 is a wasteful number, since it uses less digits than its factorization.

20291990123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186165156.

The product of its (nonzero) digits is 17496, while the sum is 38.

The spelling of 20291990123 in words is "twenty billion, two hundred ninety-one million, nine hundred ninety thousand, one hundred twenty-three".