21251101 has 4 divisors (see below), whose sum is σ = 22369600. Its totient is φ = 20132604.

The previous prime is 21251099. The next prime is 21251117. The reversal of 21251101 is 10115212.

21251101 = 374² + 375² + ... + 487².

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 21251101 - 2¹ = 21251099 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21251141) 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, 559221 + ... + 559258.

It is an arithmetic number, because the mean of its divisors is an integer number (5592400).

Almost surely, 2^21251101 is an apocalyptic number.

It is an amenable number.

21251101 is a deficient number, since it is larger than the sum of its proper divisors (1118499).

21251101 is a wasteful number, since it uses less digits than its factorization.

21251101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1118498.

The product of its (nonzero) digits is 20, while the sum is 13.

The square root of 21251101 is about 4609.8916473167. The cubic root of 21251101 is about 276.9876964129.

Adding to 21251101 its reverse (10115212), we get a palindrome (31366313).

The spelling of 21251101 in words is "twenty-one million, two hundred fifty-one thousand, one hundred one".