51001221 has 4 divisors (see below), whose sum is σ = 68001632. Its totient is φ = 34000812.

The previous prime is 51001213. The next prime is 51001273. The reversal of 51001221 is 12210015.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 51001221 - 2³ = 51001213 is a prime.

It is a super-2 number, since 2×51001221² = 5202249086981682, which contains 22 as substring.

It is a Duffinian number.

51001221 is a modest number, since divided by 1221 gives 51 as remainder.

It is a junction number, because it is equal to n+sod(n) for n = 51001197 and 51001206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51001421) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8500201 + ... + 8500206.

It is an arithmetic number, because the mean of its divisors is an integer number (17000408).

Almost surely, 2^51001221 is an apocalyptic number.

It is an amenable number.

51001221 is a deficient number, since it is larger than the sum of its proper divisors (17000411).

51001221 is a wasteful number, since it uses less digits than its factorization.

51001221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17000410.

The product of its (nonzero) digits is 20, while the sum is 12.

The square root of 51001221 is about 7141.5139151303. The cubic root of 51001221 is about 370.8459363754.

Adding to 51001221 its reverse (12210015), we get a palindrome (63211236).

The spelling of 51001221 in words is "fifty-one million, one thousand, two hundred twenty-one".