21171707 has 4 divisors (see below), whose sum is σ = 22092240. Its totient is φ = 20251176.

The previous prime is 21171701. The next prime is 21171713. The reversal of 21171707 is 70717112.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21171701) and next prime (21171713).

It is a cyclic number.

It is not a de Polignac number, because 21171707 - 2¹² = 21167611 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21171701) 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, 460232 + ... + 460277.

It is an arithmetic number, because the mean of its divisors is an integer number (5523060).

Almost surely, 2^21171707 is an apocalyptic number.

21171707 is a deficient number, since it is larger than the sum of its proper divisors (920533).

21171707 is an equidigital number, since it uses as much as digits as its factorization.

21171707 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 920532.

The product of its (nonzero) digits is 686, while the sum is 26.

The square root of 21171707 is about 4601.2723240426. The cubic root of 21171707 is about 276.6423244337.

Adding to 21171707 its reverse (70717112), we get a palindrome (91888819).

The spelling of 21171707 in words is "twenty-one million, one hundred seventy-one thousand, seven hundred seven".