21229581 has 8 divisors (see below), whose sum is σ = 28331424. Its totient is φ = 14140400.

The previous prime is 21229577. The next prime is 21229589. The reversal of 21229581 is 18592212.

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 21229581 - 2² = 21229577 is a prime.

It is a super-2 number, since 2×21229581² = 901390218871122, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21229589) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1915 + ... + 6791.

It is an arithmetic number, because the mean of its divisors is an integer number (3541428).

Almost surely, 2^21229581 is an apocalyptic number.

It is an amenable number.

21229581 is a deficient number, since it is larger than the sum of its proper divisors (7101843).

21229581 is a wasteful number, since it uses less digits than its factorization.

21229581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6331.

The product of its digits is 2880, while the sum is 30.

The square root of 21229581 is about 4607.5569448462. The cubic root of 21229581 is about 276.8941673228.

The spelling of 21229581 in words is "twenty-one million, two hundred twenty-nine thousand, five hundred eighty-one".