21704137 has 16 divisors (see below), whose sum is σ = 28120960. Its totient is φ = 16267392.

The previous prime is 21704131. The next prime is 21704143. The reversal of 21704137 is 73140712.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21704131) and next prime (21704143).

It is a cyclic number.

It is not a de Polignac number, because 21704137 - 2⁷ = 21704009 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21704131) 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 15 ways as a sum of consecutive naturals, for example, 4548 + ... + 8005.

It is an arithmetic number, because the mean of its divisors is an integer number (1757560).

Almost surely, 2^21704137 is an apocalyptic number.

It is an amenable number.

21704137 is a deficient number, since it is larger than the sum of its proper divisors (6416823).

21704137 is a wasteful number, since it uses less digits than its factorization.

21704137 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12592.

The product of its (nonzero) digits is 1176, while the sum is 25.

The square root of 21704137 is about 4658.7699020235. The cubic root of 21704137 is about 278.9421692978.

Adding to 21704137 its reverse (73140712), we get a palindrome (94844849).

The spelling of 21704137 in words is "twenty-one million, seven hundred four thousand, one hundred thirty-seven".