21013542 has 24 divisors (see below), whose sum is σ = 49668840. Its totient is φ = 6367680.

The previous prime is 21013537. The next prime is 21013543. The reversal of 21013542 is 24531012.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21013543) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 52867 + ... + 53262.

It is an arithmetic number, because the mean of its divisors is an integer number (2069535).

Almost surely, 2^21013542 is an apocalyptic number.

21013542 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21013542 is an abundant number, since it is smaller than the sum of its proper divisors (28655298).

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

21013542 is a wasteful number, since it uses less digits than its factorization.

21013542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106148 (or 106145 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21013542 is about 4584.0530101647. The cubic root of 21013542 is about 275.9517086273.

Adding to 21013542 its reverse (24531012), we get a palindrome (45544554).

The spelling of 21013542 in words is "twenty-one million, thirteen thousand, five hundred forty-two".