21648137 has 8 divisors (see below), whose sum is σ = 25539072. Its totient is φ = 17956800.

The previous prime is 21648127. The next prime is 21648139. The reversal of 21648137 is 73184612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21648137 - 2¹⁰ = 21647113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21648139) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 49664 + ... + 50097.

It is an arithmetic number, because the mean of its divisors is an integer number (3192384).

Almost surely, 2^21648137 is an apocalyptic number.

It is an amenable number.

21648137 is a deficient number, since it is larger than the sum of its proper divisors (3890935).

21648137 is an equidigital number, since it uses as much as digits as its factorization.

21648137 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99799.

The product of its digits is 8064, while the sum is 32.

The square root of 21648137 is about 4652.7558500312. The cubic root of 21648137 is about 278.7020581549.

It can be divided in two parts, 2164 and 8137, that added together give a palindrome (10301).

The spelling of 21648137 in words is "twenty-one million, six hundred forty-eight thousand, one hundred thirty-seven".