21225051 has 16 divisors (see below), whose sum is σ = 31516320. Its totient is φ = 14117760.

The previous prime is 21225047. The next prime is 21225077. The reversal of 21225051 is 15052212.

It is not a de Polignac number, because 21225051 - 2² = 21225047 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21225041) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20031 + ... + 21063.

It is an arithmetic number, because the mean of its divisors is an integer number (1969770).

Almost surely, 2^21225051 is an apocalyptic number.

21225051 is a deficient number, since it is larger than the sum of its proper divisors (10291269).

21225051 is a wasteful number, since it uses less digits than its factorization.

21225051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1803 (or 1797 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 18.

The square root of 21225051 is about 4607.0653348960. The cubic root of 21225051 is about 276.8744712235.

Adding to 21225051 its reverse (15052212), we get a palindrome (36277263).

The spelling of 21225051 in words is "twenty-one million, two hundred twenty-five thousand, fifty-one".