21718154 has 4 divisors (see below), whose sum is σ = 32577234. Its totient is φ = 10859076.

The previous prime is 21718133. The next prime is 21718189. The reversal of 21718154 is 45181712.

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

It can be written as a sum of positive squares in only one way, i.e., 21576025 + 142129 = 4645^2 + 377^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5429537 + ... + 5429540.

Almost surely, 2^21718154 is an apocalyptic number.

21718154 is a deficient number, since it is larger than the sum of its proper divisors (10859080).

21718154 is a wasteful number, since it uses less digits than its factorization.

21718154 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10859079.

The product of its digits is 2240, while the sum is 29.

The square root of 21718154 is about 4660.2740262779. The cubic root of 21718154 is about 279.0022053328.

Adding to 21718154 its reverse (45181712), we get a palindrome (66899866).

The spelling of 21718154 in words is "twenty-one million, seven hundred eighteen thousand, one hundred fifty-four".