21231617 has 4 divisors (see below), whose sum is σ = 23161776. Its totient is φ = 19301460.

The previous prime is 21231611. The next prime is 21231629. The reversal of 21231617 is 71613212.

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 a cyclic number.

It is not a de Polignac number, because 21231617 - 2⁴ = 21231601 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21231592 and 21231601.

It is not an unprimeable number, because it can be changed into a prime (21231611) 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, 965063 + ... + 965084.

It is an arithmetic number, because the mean of its divisors is an integer number (5790444).

Almost surely, 2^21231617 is an apocalyptic number.

It is an amenable number.

21231617 is a deficient number, since it is larger than the sum of its proper divisors (1930159).

21231617 is a wasteful number, since it uses less digits than its factorization.

21231617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1930158.

The product of its digits is 504, while the sum is 23.

The square root of 21231617 is about 4607.7778809313. Note that the first 3 decimals coincide. The cubic root of 21231617 is about 276.9030187850.

Adding to 21231617 its reverse (71613212), we get a palindrome (92844829).

The spelling of 21231617 in words is "twenty-one million, two hundred thirty-one thousand, six hundred seventeen".