21436901 has 4 divisors (see below), whose sum is σ = 21449100. Its totient is φ = 21424704.

The previous prime is 21436873. The next prime is 21436927. The reversal of 21436901 is 10963412.

It is a Cunningham number, because it is equal to 4630²+1.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5428900 + 16008001 = 2330^2 + 4001^2 .

It is a cyclic number.

It is not a de Polignac number, because 21436901 - 2²² = 17242597 is a prime.

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

It is a Duffinian number.

It is a zygodrome in base 3.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21436931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2906 + ... + 7163.

It is an arithmetic number, because the mean of its divisors is an integer number (5362275).

Almost surely, 2^21436901 is an apocalyptic number.

It is an amenable number.

21436901 is a deficient number, since it is larger than the sum of its proper divisors (12199).

21436901 is a wasteful number, since it uses less digits than its factorization.

21436901 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12198.

The product of its (nonzero) digits is 1296, while the sum is 26.

The square root of 21436901 is about 4630.0001079914. Note that the first 3 decimals coincide. The cubic root of 21436901 is about 277.7925967146.

The spelling of 21436901 in words is "twenty-one million, four hundred thirty-six thousand, nine hundred one".