651155861 has 2 divisors, whose sum is σ = 651155862. Its totient is φ = 651155860.

The previous prime is 651155851. The next prime is 651155873. The reversal of 651155861 is 168551156.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 601720900 + 49434961 = 24530^2 + 7031^2 .

It is a cyclic number.

It is not a de Polignac number, because 651155861 - 2¹⁸ = 650893717 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (651155831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 325577930 + 325577931.

It is an arithmetic number, because the mean of its divisors is an integer number (325577931).

Almost surely, 2^651155861 is an apocalyptic number.

It is an amenable number.

651155861 is a deficient number, since it is larger than the sum of its proper divisors (1).

651155861 is an equidigital number, since it uses as much as digits as its factorization.

651155861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36000, while the sum is 38.

The square root of 651155861 is about 25517.7557986591. The cubic root of 651155861 is about 866.7522638500.

The spelling of 651155861 in words is "six hundred fifty-one million, one hundred fifty-five thousand, eight hundred sixty-one".