21682137 has 4 divisors (see below), whose sum is σ = 28909520. Its totient is φ = 14454756.

The previous prime is 21682109. The next prime is 21682139. The reversal of 21682137 is 73128612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21682137 - 2¹⁰ = 21681113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21682139) 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, 3613687 + ... + 3613692.

It is an arithmetic number, because the mean of its divisors is an integer number (7227380).

Almost surely, 2^21682137 is an apocalyptic number.

It is an amenable number.

21682137 is a deficient number, since it is larger than the sum of its proper divisors (7227383).

21682137 is an equidigital number, since it uses as much as digits as its factorization.

21682137 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7227382.

The product of its digits is 4032, while the sum is 30.

The square root of 21682137 is about 4656.4081650989. The cubic root of 21682137 is about 278.8478892327.

The spelling of 21682137 in words is "twenty-one million, six hundred eighty-two thousand, one hundred thirty-seven".