21419821 has 4 divisors (see below), whose sum is σ = 22547200. Its totient is φ = 20292444.

The previous prime is 21419807. The next prime is 21419837. The reversal of 21419821 is 12891412.

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 21419821 - 2⁵ = 21419789 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21419821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21419851) 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, 563661 + ... + 563698.

It is an arithmetic number, because the mean of its divisors is an integer number (5636800).

Almost surely, 2^21419821 is an apocalyptic number.

It is an amenable number.

21419821 is a deficient number, since it is larger than the sum of its proper divisors (1127379).

21419821 is a wasteful number, since it uses less digits than its factorization.

21419821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1127378.

The product of its digits is 1152, while the sum is 28.

The square root of 21419821 is about 4628.1552480443. The cubic root of 21419821 is about 277.7187993836.

The spelling of 21419821 in words is "twenty-one million, four hundred nineteen thousand, eight hundred twenty-one".