21290429 has 4 divisors (see below), whose sum is σ = 21865884. Its totient is φ = 20714976.

The previous prime is 21290419. The next prime is 21290441. The reversal of 21290429 is 92409212.

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

It can be written as a sum of positive squares in 2 ways, for example, as 11222500 + 10067929 = 3350^2 + 3173^2 .

It is a cyclic number.

It is not a de Polignac number, because 21290429 - 2⁸ = 21290173 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21290419) 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, 287672 + ... + 287745.

It is an arithmetic number, because the mean of its divisors is an integer number (5466471).

Almost surely, 2^21290429 is an apocalyptic number.

It is an amenable number.

21290429 is a deficient number, since it is larger than the sum of its proper divisors (575455).

21290429 is an equidigital number, since it uses as much as digits as its factorization.

21290429 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 575454.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 21290429 is about 4614.1552856400. The cubic root of 21290429 is about 277.1584586893.

The spelling of 21290429 in words is "twenty-one million, two hundred ninety thousand, four hundred twenty-nine".