21981854 has 8 divisors (see below), whose sum is σ = 33175560. Its totient is φ = 10923336.

The previous prime is 21981823. The next prime is 21981871. The reversal of 21981854 is 45818912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33389 + ... + 34040.

It is an arithmetic number, because the mean of its divisors is an integer number (4146945).

Almost surely, 2^21981854 is an apocalyptic number.

21981854 is a deficient number, since it is larger than the sum of its proper divisors (11193706).

21981854 is a wasteful number, since it uses less digits than its factorization.

21981854 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67594.

The product of its digits is 23040, while the sum is 38.

The square root of 21981854 is about 4688.4809906834. The cubic root of 21981854 is about 280.1268727752.

The spelling of 21981854 in words is "twenty-one million, nine hundred eighty-one thousand, eight hundred fifty-four".