21312051 has 8 divisors (see below), whose sum is σ = 28561104. Its totient is φ = 14135520.

The previous prime is 21312023. The next prime is 21312059. The reversal of 21312051 is 15021312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21312051 - 2⁵ = 21312019 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21312051.

It is not an unprimeable number, because it can be changed into a prime (21312059) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17440 + ... + 18621.

It is an arithmetic number, because the mean of its divisors is an integer number (3570138).

Almost surely, 2^21312051 is an apocalyptic number.

21312051 is a deficient number, since it is larger than the sum of its proper divisors (7249053).

21312051 is a wasteful number, since it uses less digits than its factorization.

21312051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36261.

The product of its (nonzero) digits is 60, while the sum is 15.

The square root of 21312051 is about 4616.4976984723. The cubic root of 21312051 is about 277.2522518933.

Adding to 21312051 its reverse (15021312), we get a palindrome (36333363).

The spelling of 21312051 in words is "twenty-one million, three hundred twelve thousand, fifty-one".