51521221 has 8 divisors (see below), whose sum is σ = 52481088. Its totient is φ = 50568000.

The previous prime is 51521209. The next prime is 51521263. The reversal of 51521221 is 12212515.

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 51521221 - 2⁵ = 51521189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51521201) 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, 15606 + ... + 18616.

It is an arithmetic number, because the mean of its divisors is an integer number (6560136).

Almost surely, 2^51521221 is an apocalyptic number.

It is an amenable number.

51521221 is a deficient number, since it is larger than the sum of its proper divisors (959867).

51521221 is a wasteful number, since it uses less digits than its factorization.

51521221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3323.

The product of its digits is 200, while the sum is 19.

The square root of 51521221 is about 7177.8284320538. The cubic root of 51521221 is about 372.1020382399.

Adding to 51521221 its reverse (12212515), we get a palindrome (63733736).

It can be divided in two parts, 515 and 21221, that added together give a triangular number (21736 = T₂₀₈).

The spelling of 51521221 in words is "fifty-one million, five hundred twenty-one thousand, two hundred twenty-one".