156021021 has 24 divisors (see below), whose sum is σ = 244867896. Its totient is φ = 95155200.

The previous prime is 156021017. The next prime is 156021037. The reversal of 156021021 is 120120651.

156021021 is a `hidden beast` number, since 1 + 560 + 2 + 102 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 1988100 + 154032921 = 1410^2 + 12411^2 .

It is not a de Polignac number, because 156021021 - 2² = 156021017 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 156020985 and 156021003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (156021721) 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 in 23 ways as a sum of consecutive naturals, for example, 7321 + ... + 19121.

It is an arithmetic number, because the mean of its divisors is an integer number (10202829).

Almost surely, 2^156021021 is an apocalyptic number.

It is an amenable number.

156021021 is a deficient number, since it is larger than the sum of its proper divisors (88846875).

156021021 is a wasteful number, since it uses less digits than its factorization.

156021021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11933 (or 11930 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

The square root of 156021021 is about 12490.8374819305. The cubic root of 156021021 is about 538.3454397194.

Adding to 156021021 its reverse (120120651), we get a palindrome (276141672).

The spelling of 156021021 in words is "one hundred fifty-six million, twenty-one thousand, twenty-one".