21251667 has 8 divisors (see below), whose sum is σ = 28411840. Its totient is φ = 14129640.

The previous prime is 21251617. The next prime is 21251669. The reversal of 21251667 is 76615212.

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

It is not a de Polignac number, because 21251667 - 2⁷ = 21251539 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21251669) 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, 8209 + ... + 10482.

It is an arithmetic number, because the mean of its divisors is an integer number (3551480).

Almost surely, 2^21251667 is an apocalyptic number.

21251667 is a deficient number, since it is larger than the sum of its proper divisors (7160173).

21251667 is a wasteful number, since it uses less digits than its factorization.

21251667 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19073.

The product of its digits is 5040, while the sum is 30.

The square root of 21251667 is about 4609.9530366371. The cubic root of 21251667 is about 276.9901554800.

Adding to 21251667 its reverse (76615212), we get a palindrome (97866879).

The spelling of 21251667 in words is "twenty-one million, two hundred fifty-one thousand, six hundred sixty-seven".