20681429 has 4 divisors (see below), whose sum is σ = 20724384. Its totient is φ = 20638476.

The previous prime is 20681407. The next prime is 20681449. The reversal of 20681429 is 92418602.

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: 92418602 = 2 ⋅46209301.

It is a cyclic number.

It is not a de Polignac number, because 20681429 - 2¹² = 20677333 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20681395 and 20681404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20681449) 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, 20747 + ... + 21720.

It is an arithmetic number, because the mean of its divisors is an integer number (5181096).

Almost surely, 2^20681429 is an apocalyptic number.

It is an amenable number.

20681429 is a deficient number, since it is larger than the sum of its proper divisors (42955).

20681429 is an equidigital number, since it uses as much as digits as its factorization.

20681429 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42954.

The product of its (nonzero) digits is 6912, while the sum is 32.

The square root of 20681429 is about 4547.6839160170. The cubic root of 20681429 is about 274.4902026247.

The spelling of 20681429 in words is "twenty million, six hundred eighty-one thousand, four hundred twenty-nine".