21305429 has 8 divisors (see below), whose sum is σ = 22705920. Its totient is φ = 19944496.

The previous prime is 21305423. The next prime is 21305461. The reversal of 21305429 is 92450312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21305429 - 2⁴ = 21305413 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21305398 and 21305407.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21305423) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8774 + ... + 10935.

It is an arithmetic number, because the mean of its divisors is an integer number (2838240).

Almost surely, 2^21305429 is an apocalyptic number.

It is an amenable number.

21305429 is a deficient number, since it is larger than the sum of its proper divisors (1400491).

21305429 is a wasteful number, since it uses less digits than its factorization.

21305429 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19779.

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 21305429 is about 4615.7804323863. The cubic root of 21305429 is about 277.2235333278.

The spelling of 21305429 in words is "twenty-one million, three hundred five thousand, four hundred twenty-nine".