21039181 has 8 divisors (see below), whose sum is σ = 22711680. Its totient is φ = 19429872.

The previous prime is 21039143. The next prime is 21039197. The reversal of 21039181 is 18193012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21039181 - 2¹⁵ = 21006413 is a prime.

It is a super-2 number, since 2×21039181² = 885294274301522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21039101) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15105 + ... + 16438.

It is an arithmetic number, because the mean of its divisors is an integer number (2838960).

Almost surely, 2^21039181 is an apocalyptic number.

It is an amenable number.

21039181 is a deficient number, since it is larger than the sum of its proper divisors (1672499).

21039181 is a wasteful number, since it uses less digits than its factorization.

21039181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31595.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 21039181 is about 4586.8487003606. The cubic root of 21039181 is about 276.0638942250.

Multiplying 21039181 by its sum of digits (25), we get a palindrome (525979525).

The spelling of 21039181 in words is "twenty-one million, thirty-nine thousand, one hundred eighty-one".