21203051 has 4 divisors (see below), whose sum is σ = 21550704. Its totient is φ = 20855400.

The previous prime is 21203041. The next prime is 21203071. The reversal of 21203051 is 15030212.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21203051 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21203011) 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 3 ways as a sum of consecutive naturals, for example, 173735 + ... + 173856.

It is an arithmetic number, because the mean of its divisors is an integer number (5387676).

Almost surely, 2^21203051 is an apocalyptic number.

21203051 is a deficient number, since it is larger than the sum of its proper divisors (347653).

21203051 is an equidigital number, since it uses as much as digits as its factorization.

21203051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 347652.

The product of its (nonzero) digits is 60, while the sum is 14.

The square root of 21203051 is about 4604.6770787972. The cubic root of 21203051 is about 276.7787770031.

Adding to 21203051 its reverse (15030212), we get a palindrome (36233263).

The spelling of 21203051 in words is "twenty-one million, two hundred three thousand, fifty-one".