21427151 has 4 divisors (see below), whose sum is σ = 21476400. Its totient is φ = 21377904.

The previous prime is 21427141. The next prime is 21427171. The reversal of 21427151 is 15172412.

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 21427151 - 2¹⁸ = 21165007 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 (21427121) 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, 23966 + ... + 24843.

It is an arithmetic number, because the mean of its divisors is an integer number (5369100).

Almost surely, 2^21427151 is an apocalyptic number.

21427151 is a deficient number, since it is larger than the sum of its proper divisors (49249).

21427151 is an equidigital number, since it uses as much as digits as its factorization.

21427151 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49248.

The product of its digits is 560, while the sum is 23.

The square root of 21427151 is about 4628.9470724993. The cubic root of 21427151 is about 277.7504748216.

Adding to 21427151 its reverse (15172412), we get a palindrome (36599563).

The spelling of 21427151 in words is "twenty-one million, four hundred twenty-seven thousand, one hundred fifty-one".