156400021 has 2 divisors, whose sum is σ = 156400022. Its totient is φ = 156400020.

The previous prime is 156400003. The next prime is 156400031. The reversal of 156400021 is 120004651.

156400021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 101787921 + 54612100 = 10089^2 + 7390^2 .

It is a cyclic number.

It is not a de Polignac number, because 156400021 - 2²⁵ = 122845589 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (156400031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 78200010 + 78200011.

It is an arithmetic number, because the mean of its divisors is an integer number (78200011).

Almost surely, 2^156400021 is an apocalyptic number.

It is an amenable number.

156400021 is a deficient number, since it is larger than the sum of its proper divisors (1).

156400021 is an equidigital number, since it uses as much as digits as its factorization.

156400021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 156400021 is about 12505.9994002878. Note that the first 3 decimals coincide. The cubic root of 156400021 is about 538.7809962733.

Adding to 156400021 its reverse (120004651), we get a palindrome (276404672).

The spelling of 156400021 in words is "one hundred fifty-six million, four hundred thousand, twenty-one".