21981142 has 8 divisors (see below), whose sum is σ = 33138000. Its totient is φ = 10935144.

The previous prime is 21981137. The next prime is 21981143. The reversal of 21981142 is 24118912.

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 21981142.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21981143) 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, 27217 + ... + 28012.

It is an arithmetic number, because the mean of its divisors is an integer number (4142250).

Almost surely, 2^21981142 is an apocalyptic number.

21981142 is a deficient number, since it is larger than the sum of its proper divisors (11156858).

21981142 is a wasteful number, since it uses less digits than its factorization.

21981142 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55430.

The product of its digits is 1152, while the sum is 28.

The square root of 21981142 is about 4688.4050592926. The cubic root of 21981142 is about 280.1238482732.

The spelling of 21981142 in words is "twenty-one million, nine hundred eighty-one thousand, one hundred forty-two".