21012451 has 8 divisors (see below), whose sum is σ = 21748608. Its totient is φ = 20280000.

The previous prime is 21012449. The next prime is 21012457. The reversal of 21012451 is 15421012.

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 21012451 - 2¹ = 21012449 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21012457) 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 7 ways as a sum of consecutive naturals, for example, 15501 + ... + 16801.

It is an arithmetic number, because the mean of its divisors is an integer number (2718576).

Almost surely, 2^21012451 is an apocalyptic number.

21012451 is a deficient number, since it is larger than the sum of its proper divisors (736157).

21012451 is a wasteful number, since it uses less digits than its factorization.

21012451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1853.

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 21012451 is about 4583.9340091236. The cubic root of 21012451 is about 275.9469328415.

Adding to 21012451 its reverse (15421012), we get a palindrome (36433463).

The spelling of 21012451 in words is "twenty-one million, twelve thousand, four hundred fifty-one".