156904021 has 2 divisors, whose sum is σ = 156904022. Its totient is φ = 156904020.

The previous prime is 156904019. The next prime is 156904049. The reversal of 156904021 is 120409651.

It is an a-pointer prime, because the next prime (156904049) can be obtained adding 156904021 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 88096996 + 68807025 = 9386^2 + 8295^2 .

It is an emirp because it is prime and its reverse (120409651) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 156904021 - 2¹ = 156904019 is a prime.

Together with 156904019, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (156904421) 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, 78452010 + 78452011.

It is an arithmetic number, because the mean of its divisors is an integer number (78452011).

Almost surely, 2^156904021 is an apocalyptic number.

156904021 is the 6696-th centered heptagonal number.

It is an amenable number.

156904021 is a deficient number, since it is larger than the sum of its proper divisors (1).

156904021 is an equidigital number, since it uses as much as digits as its factorization.

156904021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2160, while the sum is 28.

The square root of 156904021 is about 12526.1335215620. The cubic root of 156904021 is about 539.3591173751.

The spelling of 156904021 in words is "one hundred fifty-six million, nine hundred four thousand, twenty-one".