21636154 has 4 divisors (see below), whose sum is σ = 32454234. Its totient is φ = 10818076.

The previous prime is 21636143. The next prime is 21636161. The reversal of 21636154 is 45163612.

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., 13359025 + 8277129 = 3655^2 + 2877^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5409037 + ... + 5409040.

Almost surely, 2^21636154 is an apocalyptic number.

21636154 is a deficient number, since it is larger than the sum of its proper divisors (10818080).

21636154 is a wasteful number, since it uses less digits than its factorization.

21636154 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10818079.

The product of its digits is 4320, while the sum is 28.

The square root of 21636154 is about 4651.4679403388. The cubic root of 21636154 is about 278.6506248889.

Adding to 21636154 its reverse (45163612), we get a palindrome (66799766).

The spelling of 21636154 in words is "twenty-one million, six hundred thirty-six thousand, one hundred fifty-four".