21523542 has 32 divisors (see below), whose sum is σ = 45525120. Its totient is φ = 6783912.

The previous prime is 21523531. The next prime is 21523543. The reversal of 21523542 is 24532512.

It is a plaindrome in base 9.

It is a zygodrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21523543) 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 15 ways as a sum of consecutive naturals, for example, 40893 + ... + 41415.

It is an arithmetic number, because the mean of its divisors is an integer number (1422660).

Almost surely, 2^21523542 is an apocalyptic number.

21523542 is an abundant number, since it is smaller than the sum of its proper divisors (24001578).

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

21523542 is an equidigital number, since it uses as much as digits as its factorization.

21523542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 585 (or 547 counting only the distinct ones).

The product of its digits is 2400, while the sum is 24.

The square root of 21523542 is about 4639.3471523481. The cubic root of 21523542 is about 278.1663428337.

The spelling of 21523542 in words is "twenty-one million, five hundred twenty-three thousand, five hundred forty-two".