21153651 has 16 divisors (see below), whose sum is σ = 28654080. Its totient is φ = 13880160.

The previous prime is 21153637. The next prime is 21153653. The reversal of 21153651 is 15635112.

It is not a de Polignac number, because 21153651 - 2¹⁴ = 21137267 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21153653) 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 15 ways as a sum of consecutive naturals, for example, 88390 + ... + 88628.

It is an arithmetic number, because the mean of its divisors is an integer number (1790880).

Almost surely, 2^21153651 is an apocalyptic number.

21153651 is a deficient number, since it is larger than the sum of its proper divisors (7500429).

21153651 is a wasteful number, since it uses less digits than its factorization.

21153651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 586.

The product of its digits is 900, while the sum is 24.

The square root of 21153651 is about 4599.3098395303. The cubic root of 21153651 is about 276.5636585288.

Adding to 21153651 its reverse (15635112), we get a palindrome (36788763).

The spelling of 21153651 in words is "twenty-one million, one hundred fifty-three thousand, six hundred fifty-one".