651121221 has 16 divisors (see below), whose sum is σ = 893426688. Its totient is φ = 421590000.

The previous prime is 651121213. The next prime is 651121243. The reversal of 651121221 is 122121156.

651121221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 651121221 - 2³ = 651121213 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (651121291) 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, 846 + ... + 36096.

It is an arithmetic number, because the mean of its divisors is an integer number (55839168).

Almost surely, 2^651121221 is an apocalyptic number.

It is an amenable number.

651121221 is a deficient number, since it is larger than the sum of its proper divisors (242305467).

651121221 is a wasteful number, since it uses less digits than its factorization.

651121221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35432.

The product of its digits is 240, while the sum is 21.

The square root of 651121221 is about 25517.0770465584. The cubic root of 651121221 is about 866.7368938326.

Adding to 651121221 its reverse (122121156), we get a palindrome (773242377).

The spelling of 651121221 in words is "six hundred fifty-one million, one hundred twenty-one thousand, two hundred twenty-one".