21172107 has 8 divisors (see below), whose sum is σ = 30795840. Its totient is φ = 12831560.

The previous prime is 21172097. The next prime is 21172133. The reversal of 21172107 is 70127112.

It is a happy number.

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 21172107 - 2¹⁴ = 21155723 is a prime.

It is a super-2 number, since 2×21172107² = 896516229638898, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21172147) 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, 320757 + ... + 320822.

It is an arithmetic number, because the mean of its divisors is an integer number (3849480).

Almost surely, 2^21172107 is an apocalyptic number.

21172107 is a deficient number, since it is larger than the sum of its proper divisors (9623733).

21172107 is a wasteful number, since it uses less digits than its factorization.

21172107 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 641593.

The product of its (nonzero) digits is 196, while the sum is 21.

The square root of 21172107 is about 4601.3157900757. The cubic root of 21172107 is about 276.6440666367.

Adding to 21172107 its reverse (70127112), we get a palindrome (91299219).

It can be divided in two parts, 2117 and 2107, that added together give a palindrome (4224).

The spelling of 21172107 in words is "twenty-one million, one hundred seventy-two thousand, one hundred seven".