21159939 has 8 divisors (see below), whose sum is σ = 29698240. Its totient is φ = 13364136.

The previous prime is 21159923. The next prime is 21159953. The reversal of 21159939 is 93995112.

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

It is not a de Polignac number, because 21159939 - 2⁴ = 21159923 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21159897 and 21159906.

It is not an unprimeable number, because it can be changed into a prime (21159539) 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, 185557 + ... + 185670.

It is an arithmetic number, because the mean of its divisors is an integer number (3712280).

Almost surely, 2^21159939 is an apocalyptic number.

21159939 is a deficient number, since it is larger than the sum of its proper divisors (8538301).

21159939 is a wasteful number, since it uses less digits than its factorization.

21159939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 371249.

The product of its digits is 21870, while the sum is 39.

The square root of 21159939 is about 4599.9933695604. The cubic root of 21159939 is about 276.5910589998.

The spelling of 21159939 in words is "twenty-one million, one hundred fifty-nine thousand, nine hundred thirty-nine".