1620357121 has 4 divisors (see below), whose sum is σ = 1620601092. Its totient is φ = 1620113152.

The previous prime is 1620357119. The next prime is 1620357127. The reversal of 1620357121 is 1217530261.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1217530261 = 2293 ⋅530977.

It can be written as a sum of positive squares in 2 ways, for example, as 848906496 + 771450625 = 29136^2 + 27775^2 .

It is a cyclic number.

It is not a de Polignac number, because 1620357121 - 2¹ = 1620357119 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1620357121.

It is not an unprimeable number, because it can be changed into a prime (1620357127) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 111736 + ... + 125401.

It is an arithmetic number, because the mean of its divisors is an integer number (405150273).

Almost surely, 2^1620357121 is an apocalyptic number.

It is an amenable number.

1620357121 is a deficient number, since it is larger than the sum of its proper divisors (243971).

1620357121 is an equidigital number, since it uses as much as digits as its factorization.

1620357121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 243970.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 1620357121 is about 40253.6597218191. The cubic root of 1620357121 is about 1174.5465873338.

Adding to 1620357121 its reverse (1217530261), we get a palindrome (2837887382).

The spelling of 1620357121 in words is "one billion, six hundred twenty million, three hundred fifty-seven thousand, one hundred twenty-one".