21197542 has 4 divisors (see below), whose sum is σ = 31796316. Its totient is φ = 10598770.

The previous prime is 21197489. The next prime is 21197551. The reversal of 21197542 is 24579112.

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

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 as a sum of consecutive naturals, namely, 5299384 + ... + 5299387.

It is an arithmetic number, because the mean of its divisors is an integer number (7949079).

Almost surely, 2^21197542 is an apocalyptic number.

21197542 is a deficient number, since it is larger than the sum of its proper divisors (10598774).

21197542 is a wasteful number, since it uses less digits than its factorization.

21197542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10598773.

The product of its digits is 5040, while the sum is 31.

The square root of 21197542 is about 4604.0788438080. The cubic root of 21197542 is about 276.7548039381.

The spelling of 21197542 in words is "twenty-one million, one hundred ninety-seven thousand, five hundred forty-two".