656129381 has 2 divisors, whose sum is σ = 656129382. Its totient is φ = 656129380.

The previous prime is 656129377. The next prime is 656129393. The reversal of 656129381 is 183921656.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 656128225 + 1156 = 25615^2 + 34^2 .

It is a cyclic number.

It is not a de Polignac number, because 656129381 - 2² = 656129377 is a prime.

It is a super-2 number, since 2×656129381² = 861011529222886322, which contains 22 as substring.

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 (656122381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 328064690 + 328064691.

It is an arithmetic number, because the mean of its divisors is an integer number (328064691).

Almost surely, 2^656129381 is an apocalyptic number.

It is an amenable number.

656129381 is a deficient number, since it is larger than the sum of its proper divisors (1).

656129381 is an equidigital number, since it uses as much as digits as its factorization.

656129381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 77760, while the sum is 41.

The square root of 656129381 is about 25615.0225648934. The cubic root of 656129381 is about 868.9534167076.

The spelling of 656129381 in words is "six hundred fifty-six million, one hundred twenty-nine thousand, three hundred eighty-one".