21865429 has 4 divisors (see below), whose sum is σ = 21942976. Its totient is φ = 21787884.

The previous prime is 21865427. The next prime is 21865439. The reversal of 21865429 is 92456812.

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 21865429 - 2¹ = 21865427 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21865421) 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, 38349 + ... + 38914.

It is an arithmetic number, because the mean of its divisors is an integer number (5485744).

Almost surely, 2^21865429 is an apocalyptic number.

It is an amenable number.

21865429 is a deficient number, since it is larger than the sum of its proper divisors (77547).

21865429 is an equidigital number, since it uses as much as digits as its factorization.

21865429 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77546.

The product of its digits is 34560, while the sum is 37.

The square root of 21865429 is about 4676.0484385857. The cubic root of 21865429 is about 279.6314411059.

The spelling of 21865429 in words is "twenty-one million, eight hundred sixty-five thousand, four hundred twenty-nine".