21619187 has 4 divisors (see below), whose sum is σ = 21635520. Its totient is φ = 21602856.

The previous prime is 21619159. The next prime is 21619217. The reversal of 21619187 is 78191612.

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 21619187 - 2¹⁸ = 21357043 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21619127) 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, 5987 + ... + 8892.

It is an arithmetic number, because the mean of its divisors is an integer number (5408880).

Almost surely, 2^21619187 is an apocalyptic number.

21619187 is a deficient number, since it is larger than the sum of its proper divisors (16333).

21619187 is a wasteful number, since it uses less digits than its factorization.

21619187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16332.

The product of its digits is 6048, while the sum is 35.

The square root of 21619187 is about 4649.6437497942. The cubic root of 21619187 is about 278.5777668762.

The spelling of 21619187 in words is "twenty-one million, six hundred nineteen thousand, one hundred eighty-seven".