156820681 has 2 divisors, whose sum is σ = 156820682. Its totient is φ = 156820680.

The previous prime is 156820679. The next prime is 156820711. The reversal of 156820681 is 186028651.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 149230656 + 7590025 = 12216^2 + 2755^2 .

It is a cyclic number.

It is not a de Polignac number, because 156820681 - 2¹ = 156820679 is a prime.

It is a super-2 number, since 2×156820681² = 49185451978607522, which contains 22 as substring.

Together with 156820679, it forms a pair of twin primes.

It is equal to p_8806159 and since 156820681 and 8806159 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 156820681.

It is not a weakly prime, because it can be changed into another prime (156820381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 78410340 + 78410341.

It is an arithmetic number, because the mean of its divisors is an integer number (78410341).

Almost surely, 2^156820681 is an apocalyptic number.

It is an amenable number.

156820681 is a deficient number, since it is larger than the sum of its proper divisors (1).

156820681 is an equidigital number, since it uses as much as digits as its factorization.

156820681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23040, while the sum is 37.

The square root of 156820681 is about 12522.8064346615. The cubic root of 156820681 is about 539.2636064393.

The spelling of 156820681 in words is "one hundred fifty-six million, eight hundred twenty thousand, six hundred eighty-one".