21535451 has 12 divisors (see below), whose sum is σ = 25156152. Its totient is φ = 18381888.

The previous prime is 21535433. The next prime is 21535477. The reversal of 21535451 is 15453512.

It is not a de Polignac number, because 21535451 - 2¹⁴ = 21519067 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21535451.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21535411) 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 11 ways as a sum of consecutive naturals, for example, 13091 + ... + 14643.

It is an arithmetic number, because the mean of its divisors is an integer number (2096346).

Almost surely, 2^21535451 is an apocalyptic number.

21535451 is a deficient number, since it is larger than the sum of its proper divisors (3620701).

21535451 is a wasteful number, since it uses less digits than its factorization.

21535451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1850 (or 1843 counting only the distinct ones).

The product of its digits is 3000, while the sum is 26.

The square root of 21535451 is about 4640.6304528587. The cubic root of 21535451 is about 278.2176366246.

Adding to 21535451 its reverse (15453512), we get a palindrome (36988963).

The spelling of 21535451 in words is "twenty-one million, five hundred thirty-five thousand, four hundred fifty-one".