21987411 has 8 divisors (see below), whose sum is σ = 29342160. Its totient is φ = 14645472.

The previous prime is 21987403. The next prime is 21987461. The reversal of 21987411 is 11478912.

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

It is not a de Polignac number, because 21987411 - 2³ = 21987403 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21987461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2025 + ... + 6933.

It is an arithmetic number, because the mean of its divisors is an integer number (3667770).

Almost surely, 2^21987411 is an apocalyptic number.

21987411 is a deficient number, since it is larger than the sum of its proper divisors (7354749).

21987411 is a wasteful number, since it uses less digits than its factorization.

21987411 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6405.

The product of its digits is 4032, while the sum is 33.

The square root of 21987411 is about 4689.0735758783. The cubic root of 21987411 is about 280.1504760903.

The spelling of 21987411 in words is "twenty-one million, nine hundred eighty-seven thousand, four hundred eleven".