21339571 has 4 divisors (see below), whose sum is σ = 23279544. Its totient is φ = 19399600.

The previous prime is 21339553. The next prime is 21339581. The reversal of 21339571 is 17593312.

It is a semiprime because it is the product of two primes.

It is a de Polignac number, because none of the positive numbers 2^k-21339571 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21339511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 969970 + ... + 969991.

It is an arithmetic number, because the mean of its divisors is an integer number (5819886).

Almost surely, 2^21339571 is an apocalyptic number.

21339571 is a deficient number, since it is larger than the sum of its proper divisors (1939973).

21339571 is a wasteful number, since it uses less digits than its factorization.

21339571 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1939972.

The product of its digits is 5670, while the sum is 31.

The square root of 21339571 is about 4619.4773513894. The cubic root of 21339571 is about 277.3715380843.

The spelling of 21339571 in words is "twenty-one million, three hundred thirty-nine thousand, five hundred seventy-one".