21436649 has 8 divisors (see below), whose sum is σ = 23121672. Its totient is φ = 19756800.

The previous prime is 21436637. The next prime is 21436651. The reversal of 21436649 is 94663412.

It can be written as a sum of positive squares in 4 ways, for example, as 570025 + 20866624 = 755^2 + 4568^2 .

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 21436649 - 2¹² = 21432553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21436549) 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, 14927 + ... + 16299.

It is an arithmetic number, because the mean of its divisors is an integer number (2890209).

Almost surely, 2^21436649 is an apocalyptic number.

It is an amenable number.

21436649 is a deficient number, since it is larger than the sum of its proper divisors (1685023).

21436649 is a wasteful number, since it uses less digits than its factorization.

21436649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2587.

The product of its digits is 31104, while the sum is 35.

The square root of 21436649 is about 4629.9728940891. The cubic root of 21436649 is about 277.7915081865.

It can be divided in two parts, 214 and 36649, that added together give a palindrome (36863).

The spelling of 21436649 in words is "twenty-one million, four hundred thirty-six thousand, six hundred forty-nine".