21440429 has 4 divisors (see below), whose sum is σ = 21454080. Its totient is φ = 21426780.

The previous prime is 21440411. The next prime is 21440431. The reversal of 21440429 is 92404412.

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.

It is a cyclic number.

It is not a de Polignac number, because 21440429 - 2¹² = 21436333 is a prime.

It is a Duffinian number.

It is a plaindrome in base 11.

It is a junction number, because it is equal to n+sod(n) for n = 21440398 and 21440407.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21440449) 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, 4109 + ... + 7730.

It is an arithmetic number, because the mean of its divisors is an integer number (5363520).

Almost surely, 2^21440429 is an apocalyptic number.

It is an amenable number.

21440429 is a deficient number, since it is larger than the sum of its proper divisors (13651).

21440429 is a wasteful number, since it uses less digits than its factorization.

21440429 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13650.

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 21440429 is about 4630.3810858287. The cubic root of 21440429 is about 277.8078352127.

The spelling of 21440429 in words is "twenty-one million, four hundred forty thousand, four hundred twenty-nine".