21000451 has 8 divisors (see below), whose sum is σ = 21406464. Its totient is φ = 20597640.

The previous prime is 21000433. The next prime is 21000461. The reversal of 21000451 is 15400012.

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 21000451 - 2⁹ = 20999939 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21000461) 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, 15466 + ... + 16768.

It is an arithmetic number, because the mean of its divisors is an integer number (2675808).

Almost surely, 2^21000451 is an apocalyptic number.

21000451 is a deficient number, since it is larger than the sum of its proper divisors (406013).

21000451 is a wasteful number, since it uses less digits than its factorization.

21000451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1601.

The product of its (nonzero) digits is 40, while the sum is 13.

The square root of 21000451 is about 4582.6249028259. The cubic root of 21000451 is about 275.8943926633.

Adding to 21000451 its reverse (15400012), we get a palindrome (36400463).

The spelling of 21000451 in words is "twenty-one million, four hundred fifty-one", and thus it is an aban number.