21191854 has 4 divisors (see below), whose sum is σ = 31787784. Its totient is φ = 10595926.

The previous prime is 21191831. The next prime is 21191857. The reversal of 21191854 is 45819112.

It is a happy number.

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 (21191857) 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, 5297962 + ... + 5297965.

It is an arithmetic number, because the mean of its divisors is an integer number (7946946).

Almost surely, 2^21191854 is an apocalyptic number.

21191854 is a deficient number, since it is larger than the sum of its proper divisors (10595930).

21191854 is a wasteful number, since it uses less digits than its factorization.

21191854 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10595929.

The product of its digits is 2880, while the sum is 31.

The square root of 21191854 is about 4603.4610892241. The cubic root of 21191854 is about 276.7300475749.

The spelling of 21191854 in words is "twenty-one million, one hundred ninety-one thousand, eight hundred fifty-four".