21427137 has 6 divisors (see below), whose sum is σ = 30950322. Its totient is φ = 14284752.

The previous prime is 21427129. The next prime is 21427139. The reversal of 21427137 is 73172412.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 18870336 + 2556801 = 4344^2 + 1599^2 .

It is not a de Polignac number, because 21427137 - 2³ = 21427129 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21427137.

It is not an unprimeable number, because it can be changed into a prime (21427139) by changing a digit.

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 in 5 ways as a sum of consecutive naturals, for example, 1190388 + ... + 1190405.

It is an arithmetic number, because the mean of its divisors is an integer number (5158387).

Almost surely, 2^21427137 is an apocalyptic number.

It is an amenable number.

21427137 is a deficient number, since it is larger than the sum of its proper divisors (9523185).

21427137 is a wasteful number, since it uses less digits than its factorization.

21427137 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2380799 (or 2380796 counting only the distinct ones).

The product of its digits is 2352, while the sum is 27.

The square root of 21427137 is about 4628.9455602761. The cubic root of 21427137 is about 277.7504143297.

Adding to 21427137 its reverse (73172412), we get a palindrome (94599549).

The spelling of 21427137 in words is "twenty-one million, four hundred twenty-seven thousand, one hundred thirty-seven".