21221154 has 12 divisors (see below), whose sum is σ = 45979206. Its totient is φ = 7073712.

The previous prime is 21221153. The next prime is 21221171. The reversal of 21221154 is 45112212.

It can be written as a sum of positive squares in only one way, i.e., 21206025 + 15129 = 4605^2 + 123^2 .

It is a Harshad number since it is a multiple of its sum of digits (18), and also a Moran number because the ratio is a prime number: 1178953 = 21221154 / (2 + 1 + 2 + 2 + 1 + 1 + 5 + 4).

It is not an unprimeable number, because it can be changed into a prime (21221153) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 589459 + ... + 589494.

Almost surely, 2^21221154 is an apocalyptic number.

21221154 is an abundant number, since it is smaller than the sum of its proper divisors (24758052).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21221154 is a wasteful number, since it uses less digits than its factorization.

21221154 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1178961 (or 1178958 counting only the distinct ones).

The product of its digits is 160, while the sum is 18.

The square root of 21221154 is about 4606.6423781318. The cubic root of 21221154 is about 276.8575251180.

Adding to 21221154 its reverse (45112212), we get a palindrome (66333366).

The spelling of 21221154 in words is "twenty-one million, two hundred twenty-one thousand, one hundred fifty-four".