21125001 has 8 divisors (see below), whose sum is σ = 28231200. Its totient is φ = 14051072.

The previous prime is 21124993. The next prime is 21125003. The reversal of 21125001 is 10052112.

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 21125001 - 2³ = 21124993 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21125003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6495 + ... + 9188.

It is an arithmetic number, because the mean of its divisors is an integer number (3528900).

Almost surely, 2^21125001 is an apocalyptic number.

It is an amenable number.

21125001 is a deficient number, since it is larger than the sum of its proper divisors (7106199).

21125001 is a wasteful number, since it uses less digits than its factorization.

21125001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16135.

The product of its (nonzero) digits is 20, while the sum is 12.

The square root of 21125001 is about 4596.1941864982. The cubic root of 21125001 is about 276.4387450459.

Adding to 21125001 its reverse (10052112), we get a palindrome (31177113).

The spelling of 21125001 in words is "twenty-one million, one hundred twenty-five thousand, one".