21786429 has 12 divisors (see below), whose sum is σ = 33791424. Its totient is φ = 12449304.

The previous prime is 21786403. The next prime is 21786437. The reversal of 21786429 is 92468712.

It is not a de Polignac number, because 21786429 - 2⁷ = 21786301 is a prime.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21786449) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 73957 + ... + 74250.

It is an arithmetic number, because the mean of its divisors is an integer number (2815952).

Almost surely, 2^21786429 is an apocalyptic number.

It is an amenable number.

21786429 is a deficient number, since it is larger than the sum of its proper divisors (12004995).

21786429 is a wasteful number, since it uses less digits than its factorization.

21786429 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 148224 (or 148217 counting only the distinct ones).

The product of its digits is 48384, while the sum is 39.

The square root of 21786429 is about 4667.5934912972. The cubic root of 21786429 is about 279.2942643655.

The spelling of 21786429 in words is "twenty-one million, seven hundred eighty-six thousand, four hundred twenty-nine".