21011481 has 12 divisors (see below), whose sum is σ = 31474352. Its totient is φ = 14007492.

The previous prime is 21011453. The next prime is 21011503. The reversal of 21011481 is 18411012.

It is a de Polignac number, because none of the positive numbers 2^k-21011481 is a prime.

It is a super-2 number, since 2×21011481² = 882964667626722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21011411) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 42991 + ... + 43476.

Almost surely, 2^21011481 is an apocalyptic number.

It is an amenable number.

21011481 is a deficient number, since it is larger than the sum of its proper divisors (10462871).

21011481 is an frugal number, since it uses more digits than its factorization.

21011481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86482 (or 86470 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

The square root of 21011481 is about 4583.8282035870. The cubic root of 21011481 is about 275.9426865870.

Adding to 21011481 its reverse (18411012), we get a palindrome (39422493).

The spelling of 21011481 in words is "twenty-one million, eleven thousand, four hundred eighty-one".