21867919 has 4 divisors (see below), whose sum is σ = 21883120. Its totient is φ = 21852720.

The previous prime is 21867913. The next prime is 21867931. The reversal of 21867919 is 91976812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21867919 - 2²¹ = 19770767 is a prime.

It is a super-2 number, since 2×21867919² = 956411762781122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21867913) 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, 5187 + ... + 8404.

It is an arithmetic number, because the mean of its divisors is an integer number (5470780).

Almost surely, 2^21867919 is an apocalyptic number.

21867919 is a deficient number, since it is larger than the sum of its proper divisors (15201).

21867919 is a wasteful number, since it uses less digits than its factorization.

21867919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15200.

The product of its digits is 54432, while the sum is 43.

The square root of 21867919 is about 4676.3146814559. The cubic root of 21867919 is about 279.6420553631.

The spelling of 21867919 in words is "twenty-one million, eight hundred sixty-seven thousand, nine hundred nineteen".