21403542 has 16 divisors (see below), whose sum is σ = 43323840. Its totient is φ = 7048392.

The previous prime is 21403483. The next prime is 21403559. The reversal of 21403542 is 24530412.

It is a super-2 number, since 2×21403542² = 916223220291528, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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, 20992 + ... + 21987.

It is an arithmetic number, because the mean of its divisors is an integer number (2707740).

Almost surely, 2^21403542 is an apocalyptic number.

21403542 is an abundant number, since it is smaller than the sum of its proper divisors (21920298).

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

21403542 is a wasteful number, since it uses less digits than its factorization.

21403542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43067.

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

The square root of 21403542 is about 4626.3962216827. The cubic root of 21403542 is about 277.6484264001.

Adding to 21403542 its reverse (24530412), we get a palindrome (45933954).

It can be divided in two parts, 21403 and 542, that added together give a triangular number (21945 = T₂₀₉).

The spelling of 21403542 in words is "twenty-one million, four hundred three thousand, five hundred forty-two".