21981574 has 4 divisors (see below), whose sum is σ = 32972364. Its totient is φ = 10990786.

The previous prime is 21981569. The next prime is 21981577. The reversal of 21981574 is 47518912.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21981577) by changing a digit.

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, 5495392 + ... + 5495395.

It is an arithmetic number, because the mean of its divisors is an integer number (8243091).

Almost surely, 2^21981574 is an apocalyptic number.

21981574 is a deficient number, since it is larger than the sum of its proper divisors (10990790).

21981574 is a wasteful number, since it uses less digits than its factorization.

21981574 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10990789.

The product of its digits is 20160, while the sum is 37.

The square root of 21981574 is about 4688.4511301708. The cubic root of 21981574 is about 280.1256833721.

The spelling of 21981574 in words is "twenty-one million, nine hundred eighty-one thousand, five hundred seventy-four".