20892991 has 4 divisors (see below), whose sum is σ = 23877712. Its totient is φ = 17908272.

The previous prime is 20892979. The next prime is 20893001. The reversal of 20892991 is 19929802.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20892991 - 2¹⁷ = 20761919 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20892931) 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, 1492350 + ... + 1492363.

It is an arithmetic number, because the mean of its divisors is an integer number (5969428).

Almost surely, 2^20892991 is an apocalyptic number.

20892991 is a deficient number, since it is larger than the sum of its proper divisors (2984721).

20892991 is an equidigital number, since it uses as much as digits as its factorization.

20892991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2984720.

The product of its (nonzero) digits is 23328, while the sum is 40.

The square root of 20892991 is about 4570.8851440394. The cubic root of 20892991 is about 275.4230008036.

The spelling of 20892991 in words is "twenty million, eight hundred ninety-two thousand, nine hundred ninety-one".