21358729 has 8 divisors (see below), whose sum is σ = 24774848. Its totient is φ = 18033840.

The previous prime is 21358699. The next prime is 21358739. The reversal of 21358729 is 92785312.

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 21358729 - 2²¹ = 19261577 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21358739) 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, 22302 + ... + 23239.

It is an arithmetic number, because the mean of its divisors is an integer number (3096856).

Almost surely, 2^21358729 is an apocalyptic number.

It is an amenable number.

21358729 is a deficient number, since it is larger than the sum of its proper divisors (3416119).

21358729 is an equidigital number, since it uses as much as digits as its factorization.

21358729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45615.

The product of its digits is 30240, while the sum is 37.

The square root of 21358729 is about 4621.5504973980. The cubic root of 21358729 is about 277.4545184233.

The spelling of 21358729 in words is "twenty-one million, three hundred fifty-eight thousand, seven hundred twenty-nine".