21252101 has 8 divisors (see below), whose sum is σ = 22979544. Its totient is φ = 19537920.

The previous prime is 21252079. The next prime is 21252107. The reversal of 21252101 is 10125212.

It is a Cunningham number, because it is equal to 4610²+1.

21252101 is an esthetic number in base 7, because in such base its adjacent digits differ by 1.

It can be written as a sum of positive squares in 4 ways, for example, as 3147076 + 18105025 = 1774^2 + 4255^2 .

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 21252101 - 2¹⁰ = 21251077 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21252107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 161 + ... + 6521.

It is an arithmetic number, because the mean of its divisors is an integer number (2872443).

Almost surely, 2^21252101 is an apocalyptic number.

It is an amenable number.

21252101 is a deficient number, since it is larger than the sum of its proper divisors (1727443).

21252101 is a wasteful number, since it uses less digits than its factorization.

21252101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6631.

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 21252101 is about 4610.0001084599. Note that the first 3 decimals coincide. The cubic root of 21252101 is about 276.9920410247.

Adding to 21252101 its reverse (10125212), we get a palindrome (31377313).

The spelling of 21252101 in words is "twenty-one million, two hundred fifty-two thousand, one hundred one".