20981542 has 4 divisors (see below), whose sum is σ = 31472316. Its totient is φ = 10490770.

The previous prime is 20981537. The next prime is 20981551. The reversal of 20981542 is 24518902.

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, 5245384 + ... + 5245387.

It is an arithmetic number, because the mean of its divisors is an integer number (7868079).

Almost surely, 2^20981542 is an apocalyptic number.

20981542 is a deficient number, since it is larger than the sum of its proper divisors (10490774).

20981542 is a wasteful number, since it uses less digits than its factorization.

20981542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10490773.

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

The square root of 20981542 is about 4580.5613193145. The cubic root of 20981542 is about 275.8115618449.

The spelling of 20981542 in words is "twenty million, nine hundred eighty-one thousand, five hundred forty-two".