21989619 has 24 divisors (see below), whose sum is σ = 33988032. Its totient is φ = 13651200.

The previous prime is 21989599. The next prime is 21989621. The reversal of 21989619 is 91698912.

21989619 is a `hidden beast` number, since 21 + 9 + 8 + 9 + 619 = 666.

It is not a de Polignac number, because 21989619 - 2⁷ = 21989491 is a prime.

It is a super-2 number, since 2×21989619² = 967086687530322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21989659) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14742 + ... + 16164.

It is an arithmetic number, because the mean of its divisors is an integer number (1416168).

Almost surely, 2^21989619 is an apocalyptic number.

21989619 is a deficient number, since it is larger than the sum of its proper divisors (11998413).

21989619 is a wasteful number, since it uses less digits than its factorization.

21989619 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1547 (or 1544 counting only the distinct ones).

The product of its digits is 69984, while the sum is 45.

The square root of 21989619 is about 4689.3090109311. The cubic root of 21989619 is about 280.1598534494.

The spelling of 21989619 in words is "twenty-one million, nine hundred eighty-nine thousand, six hundred nineteen".