21115481 has 4 divisors (see below), whose sum is σ = 21196032. Its totient is φ = 21034932.

The previous prime is 21115453. The next prime is 21115511. The reversal of 21115481 is 18451112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21115481 - 2⁶ = 21115417 is a prime.

It is a super-2 number, since 2×21115481² = 891727075722722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21115421) 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, 39881 + ... + 40406.

It is an arithmetic number, because the mean of its divisors is an integer number (5299008).

Almost surely, 2^21115481 is an apocalyptic number.

It is an amenable number.

21115481 is a deficient number, since it is larger than the sum of its proper divisors (80551).

21115481 is an equidigital number, since it uses as much as digits as its factorization.

21115481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80550.

The product of its digits is 320, while the sum is 23.

The square root of 21115481 is about 4595.1584303482. The cubic root of 21115481 is about 276.3972130198.

Adding to 21115481 its reverse (18451112), we get a palindrome (39566593).

The spelling of 21115481 in words is "twenty-one million, one hundred fifteen thousand, four hundred eighty-one".