21040451 has 4 divisors (see below), whose sum is σ = 21055152. Its totient is φ = 21025752.

The previous prime is 21040447. The next prime is 21040463. The reversal of 21040451 is 15404012.

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

It is a cyclic number.

It is not a de Polignac number, because 21040451 - 2² = 21040447 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21040651) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4940 + ... + 8153.

It is an arithmetic number, because the mean of its divisors is an integer number (5263788).

Almost surely, 2^21040451 is an apocalyptic number.

21040451 is a deficient number, since it is larger than the sum of its proper divisors (14701).

21040451 is a wasteful number, since it uses less digits than its factorization.

21040451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14700.

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21040451 is about 4586.9871375446. The cubic root of 21040451 is about 276.0694488470.

Adding to 21040451 its reverse (15404012), we get a palindrome (36444463).

The spelling of 21040451 in words is "twenty-one million, forty thousand, four hundred fifty-one".