1636121601 has 27 divisors (see below), whose sum is σ = 2405204451. Its totient is φ = 1071736704.

The previous prime is 1636121587. The next prime is 1636121603. The reversal of 1636121601 is 1061216361.

The square root of 1636121601 is 40449.

It is a perfect power (a square), and thus also a powerful number.

1636121601 is a `hidden beast` number, since 1 + 6 + 36 + 1 + 21 + 601 = 666.

It can be written as a sum of positive squares in only one way, i.e., 734681025 + 901440576 = 27105^2 + 30024^2 .

It is not a de Polignac number, because 1636121601 - 2²¹ = 1634024449 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1636121603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 11770590 + ... + 11770728.

Almost surely, 2^1636121601 is an apocalyptic number.

1636121601 is the 40449-th square number.

1636121601 is the 20225-th centered octagonal number.

It is an amenable number.

1636121601 is a deficient number, since it is larger than the sum of its proper divisors (769082850).

1636121601 is an frugal number, since it uses more digits than its factorization.

1636121601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 478 (or 239 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The cubic root of 1636121601 is about 1178.3433616277.

Multiplying 1636121601 by its product of nonzero digits (1296), we get a square (2120413594896 = 1456164²).

Adding to 1636121601 its reverse (1061216361), we get a palindrome (2697337962).

The spelling of 1636121601 in words is "one billion, six hundred thirty-six million, one hundred twenty-one thousand, six hundred one".