21019689 has 8 divisors (see below), whose sum is σ = 31140320. Its totient is φ = 14013108.

The previous prime is 21019657. The next prime is 21019699. The reversal of 21019689 is 98691012.

It is not a de Polignac number, because 21019689 - 2⁵ = 21019657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21019699) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 389227 + ... + 389280.

It is an arithmetic number, because the mean of its divisors is an integer number (3892540).

Almost surely, 2^21019689 is an apocalyptic number.

It is an amenable number.

21019689 is a deficient number, since it is larger than the sum of its proper divisors (10120631).

21019689 is an equidigital number, since it uses as much as digits as its factorization.

21019689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 778516 (or 778510 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 21019689 is about 4584.7234376787. The cubic root of 21019689 is about 275.9786136548.

The spelling of 21019689 in words is "twenty-one million, nineteen thousand, six hundred eighty-nine".