21158542 has 8 divisors (see below), whose sum is σ = 32512032. Its totient is φ = 10321200.

The previous prime is 21158519. The next prime is 21158549. The reversal of 21158542 is 24585112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21158542.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21158549) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 128934 + ... + 129097.

It is an arithmetic number, because the mean of its divisors is an integer number (4064004).

Almost surely, 2^21158542 is an apocalyptic number.

21158542 is a deficient number, since it is larger than the sum of its proper divisors (11353490).

21158542 is a wasteful number, since it uses less digits than its factorization.

21158542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258074.

The product of its digits is 3200, while the sum is 28.

The square root of 21158542 is about 4599.8415190091. The cubic root of 21158542 is about 276.5849719278.

The spelling of 21158542 in words is "twenty-one million, one hundred fifty-eight thousand, five hundred forty-two".