21503442 has 16 divisors (see below), whose sum is σ = 44490240. Its totient is φ = 6920592.

The previous prime is 21503437. The next prime is 21503467. The reversal of 21503442 is 24430512.

It is an unprimeable number.

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, 61618 + ... + 61965.

It is an arithmetic number, because the mean of its divisors is an integer number (2780640).

Almost surely, 2^21503442 is an apocalyptic number.

21503442 is an abundant number, since it is smaller than the sum of its proper divisors (22986798).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21503442 is a wasteful number, since it uses less digits than its factorization.

21503442 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123617.

The product of its (nonzero) digits is 960, while the sum is 21.

The square root of 21503442 is about 4637.1803932994. The cubic root of 21503442 is about 278.0797262838.

Adding to 21503442 its reverse (24430512), we get a palindrome (45933954).

It can be divided in two parts, 21503 and 442, that added together give a triangular number (21945 = T₂₀₉).

The spelling of 21503442 in words is "twenty-one million, five hundred three thousand, four hundred forty-two".