651161821 has 2 divisors, whose sum is σ = 651161822. Its totient is φ = 651161820.

The previous prime is 651161767. The next prime is 651161837. The reversal of 651161821 is 128161156.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 649536196 + 1625625 = 25486^2 + 1275^2 .

It is a cyclic number.

It is not a de Polignac number, because 651161821 - 2²⁷ = 516944093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (651161881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 325580910 + 325580911.

It is an arithmetic number, because the mean of its divisors is an integer number (325580911).

Almost surely, 2^651161821 is an apocalyptic number.

It is an amenable number.

651161821 is a deficient number, since it is larger than the sum of its proper divisors (1).

651161821 is an equidigital number, since it uses as much as digits as its factorization.

651161821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2880, while the sum is 31.

The square root of 651161821 is about 25517.8725798214. The cubic root of 651161821 is about 866.7549082900.

The spelling of 651161821 in words is "six hundred fifty-one million, one hundred sixty-one thousand, eight hundred twenty-one".