20811929 has 4 divisors (see below), whose sum is σ = 21254784. Its totient is φ = 20369076.

The previous prime is 20811911. The next prime is 20811953. The reversal of 20811929 is 92911802.

It is a happy number.

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, and also an emirpimes, since its reverse is a distinct semiprime: 92911802 = 2 ⋅46455901.

It is a cyclic number.

It is not a de Polignac number, because 20811929 - 2¹² = 20807833 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20811895 and 20811904.

It is not an unprimeable number, because it can be changed into a prime (20811229) 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, 221357 + ... + 221450.

It is an arithmetic number, because the mean of its divisors is an integer number (5313696).

Almost surely, 2^20811929 is an apocalyptic number.

It is an amenable number.

20811929 is a deficient number, since it is larger than the sum of its proper divisors (442855).

20811929 is an equidigital number, since it uses as much as digits as its factorization.

20811929 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 442854.

The product of its (nonzero) digits is 2592, while the sum is 32.

The square root of 20811929 is about 4562.0093160799. The cubic root of 20811929 is about 275.0663377152.

The spelling of 20811929 in words is "twenty million, eight hundred eleven thousand, nine hundred twenty-nine".