21654151 has 4 divisors (see below), whose sum is σ = 22352704. Its totient is φ = 20955600.

The previous prime is 21654131. The next prime is 21654161. The reversal of 21654151 is 15145612.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21654151 - 2¹⁹ = 21129863 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21654131) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 349230 + ... + 349291.

It is an arithmetic number, because the mean of its divisors is an integer number (5588176).

Almost surely, 2^21654151 is an apocalyptic number.

21654151 is a deficient number, since it is larger than the sum of its proper divisors (698553).

21654151 is an equidigital number, since it uses as much as digits as its factorization.

21654151 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 698552.

The product of its digits is 1200, while the sum is 25.

The square root of 21654151 is about 4653.4020887948. The cubic root of 21654151 is about 278.7278642091.

Adding to 21654151 its reverse (15145612), we get a palindrome (36799763).

The spelling of 21654151 in words is "twenty-one million, six hundred fifty-four thousand, one hundred fifty-one".