21438154 has 4 divisors (see below), whose sum is σ = 32157234. Its totient is φ = 10719076.

The previous prime is 21438103. The next prime is 21438187. The reversal of 21438154 is 45183412.

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., 10725625 + 10712529 = 3275^2 + 3273^2 .

It is an unprimeable number.

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, 5359537 + ... + 5359540.

Almost surely, 2^21438154 is an apocalyptic number.

21438154 is a deficient number, since it is larger than the sum of its proper divisors (10719080).

21438154 is a wasteful number, since it uses less digits than its factorization.

21438154 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10719079.

The product of its digits is 3840, while the sum is 28.

The square root of 21438154 is about 4630.1354191859. The cubic root of 21438154 is about 277.7980089917.

The spelling of 21438154 in words is "twenty-one million, four hundred thirty-eight thousand, one hundred fifty-four".