21181713 has 16 divisors (see below), whose sum is σ = 33976320. Its totient is φ = 11466576.

The previous prime is 21181703. The next prime is 21181729. The reversal of 21181713 is 31718112.

It is a happy number.

It is not a de Polignac number, because 21181713 - 2⁴ = 21181697 is a prime.

It is a super-2 number, since 2×21181713² = 897329931228738, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21181703) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26145 + ... + 26942.

It is an arithmetic number, because the mean of its divisors is an integer number (2123520).

Almost surely, 2^21181713 is an apocalyptic number.

It is an amenable number.

21181713 is a deficient number, since it is larger than the sum of its proper divisors (12794607).

21181713 is a wasteful number, since it uses less digits than its factorization.

21181713 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53116.

The product of its digits is 336, while the sum is 24.

The square root of 21181713 is about 4602.3595035590. The cubic root of 21181713 is about 276.6858990517.

Adding to 21181713 its reverse (31718112), we get a palindrome (52899825).

The spelling of 21181713 in words is "twenty-one million, one hundred eighty-one thousand, seven hundred thirteen".