21162571 has 4 divisors (see below), whose sum is σ = 21285072. Its totient is φ = 21040072.

The previous prime is 21162551. The next prime is 21162613. The reversal of 21162571 is 17526112.

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

It is a cyclic number.

It is not a de Polignac number, because 21162571 - 2⁵ = 21162539 is a prime.

It is a super-2 number, since 2×21162571² = 895708822660082, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21162521) 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, 60991 + ... + 61336.

It is an arithmetic number, because the mean of its divisors is an integer number (5321268).

Almost surely, 2^21162571 is an apocalyptic number.

21162571 is a deficient number, since it is larger than the sum of its proper divisors (122501).

21162571 is a wasteful number, since it uses less digits than its factorization.

21162571 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122500.

The product of its digits is 840, while the sum is 25.

The square root of 21162571 is about 4600.2794480336. The cubic root of 21162571 is about 276.6025265421.

Adding to 21162571 its reverse (17526112), we get a palindrome (38688683).

The spelling of 21162571 in words is "twenty-one million, one hundred sixty-two thousand, five hundred seventy-one".