21219887 has 8 divisors (see below), whose sum is σ = 23227680. Its totient is φ = 19265760.

The previous prime is 21219883. The next prime is 21219901. The reversal of 21219887 is 78891212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21219887 - 2² = 21219883 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 21219887.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21219883) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12587 + ... + 14172.

It is an arithmetic number, because the mean of its divisors is an integer number (2903460).

Almost surely, 2^21219887 is an apocalyptic number.

21219887 is a deficient number, since it is larger than the sum of its proper divisors (2007793).

21219887 is a wasteful number, since it uses less digits than its factorization.

21219887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26833.

The product of its digits is 16128, while the sum is 38.

The square root of 21219887 is about 4606.5048572643. The cubic root of 21219887 is about 276.8520151213.

The spelling of 21219887 in words is "twenty-one million, two hundred nineteen thousand, eight hundred eighty-seven".