21349845 has 48 divisors (see below), whose sum is σ = 41751360. Its totient is φ = 10343520.

The previous prime is 21349837. The next prime is 21349847. The reversal of 21349845 is 54894312.

21349845 is a nontrivial binomial coefficient, being equal to C(6535, 2).

It is not a de Polignac number, because 21349845 - 2³ = 21349837 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21349847) 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 47 ways as a sum of consecutive naturals, for example, 15682 + ... + 16988.

It is an arithmetic number, because the mean of its divisors is an integer number (869820).

Almost surely, 2^21349845 is an apocalyptic number.

21349845 is the 6534-th triangular number.

It is an amenable number.

21349845 is a deficient number, since it is larger than the sum of its proper divisors (20401515).

21349845 is a wasteful number, since it uses less digits than its factorization.

21349845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1343 (or 1326 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 21349845 is about 4620.5892481371. The cubic root of 21349845 is about 277.4160447268.

It can be divided in two parts, 21 and 349845, that added together give a triangular number (349866 = T₈₃₆).

The spelling of 21349845 in words is "twenty-one million, three hundred forty-nine thousand, eight hundred forty-five".