21369651 has 16 divisors (see below), whose sum is σ = 29611008. Its totient is φ = 13697600.

The previous prime is 21369617. The next prime is 21369659. The reversal of 21369651 is 15696312.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21369651 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (21369659) 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 15 ways as a sum of consecutive naturals, for example, 7510 + ... + 9956.

It is an arithmetic number, because the mean of its divisors is an integer number (1850688).

Almost surely, 2^21369651 is an apocalyptic number.

21369651 is a deficient number, since it is larger than the sum of its proper divisors (8241357).

21369651 is a wasteful number, since it uses less digits than its factorization.

21369651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2562.

The product of its digits is 9720, while the sum is 33.

The square root of 21369651 is about 4622.7319844438. The cubic root of 21369651 is about 277.5018034133.

The spelling of 21369651 in words is "twenty-one million, three hundred sixty-nine thousand, six hundred fifty-one".