21089542 has 4 divisors (see below), whose sum is σ = 31634316. Its totient is φ = 10544770.

The previous prime is 21089533. The next prime is 21089557. The reversal of 21089542 is 24598012.

It is a semiprime because it is the product of two primes.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5272384 + ... + 5272387.

It is an arithmetic number, because the mean of its divisors is an integer number (7908579).

Almost surely, 2^21089542 is an apocalyptic number.

21089542 is a deficient number, since it is larger than the sum of its proper divisors (10544774).

21089542 is a wasteful number, since it uses less digits than its factorization.

21089542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10544773.

The product of its (nonzero) digits is 5760, while the sum is 31.

The square root of 21089542 is about 4592.3351358541. The cubic root of 21089542 is about 276.2839879559.

The spelling of 21089542 in words is "twenty-one million, eighty-nine thousand, five hundred forty-two".