21308143 has 8 divisors (see below), whose sum is σ = 22329216. Its totient is φ = 20295000.

The previous prime is 21308141. The next prime is 21308149. The reversal of 21308143 is 34180312.

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 21308143 - 2¹ = 21308141 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21308141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3928 + ... + 7618.

It is an arithmetic number, because the mean of its divisors is an integer number (2791152).

Almost surely, 2^21308143 is an apocalyptic number.

21308143 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21308143 is a deficient number, since it is larger than the sum of its proper divisors (1021073).

21308143 is a wasteful number, since it uses less digits than its factorization.

21308143 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3965.

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 21308143 is about 4616.0744144782. The cubic root of 21308143 is about 277.2353042357.

Adding to 21308143 its reverse (34180312), we get a palindrome (55488455).

It can be divided in two parts, 21 and 308143, that multiplied together give a triangular number (6471003 = T₃₅₉₇).

The spelling of 21308143 in words is "twenty-one million, three hundred eight thousand, one hundred forty-three".