21421869 has 24 divisors (see below), whose sum is σ = 34008480. Its totient is φ = 11952864.

The previous prime is 21421861. The next prime is 21421903. The reversal of 21421869 is 96812412.

It is not a de Polignac number, because 21421869 - 2³ = 21421861 is a prime.

It is a super-2 number, since 2×21421869² = 917792942906322, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21421861) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4627 + ... + 8015.

It is an arithmetic number, because the mean of its divisors is an integer number (1417020).

Almost surely, 2^21421869 is an apocalyptic number.

It is an amenable number.

21421869 is a deficient number, since it is larger than the sum of its proper divisors (12586611).

21421869 is a wasteful number, since it uses less digits than its factorization.

21421869 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3449 (or 3442 counting only the distinct ones).

The product of its digits is 6912, while the sum is 33.

The square root of 21421869 is about 4628.3764972180. The cubic root of 21421869 is about 277.7276502197.

The spelling of 21421869 in words is "twenty-one million, four hundred twenty-one thousand, eight hundred sixty-nine".