1621355553 has 6 divisors (see below), whose sum is σ = 2341958034. Its totient is φ = 1080903696.

The previous prime is 1621355509. The next prime is 1621355573. The reversal of 1621355553 is 3555531261.

It can be written as a sum of positive squares in only one way, i.e., 1557723024 + 63632529 = 39468^2 + 7977^2 .

It is not a de Polignac number, because 1621355553 - 2¹³ = 1621347361 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1621355573) 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 5 ways as a sum of consecutive naturals, for example, 90075300 + ... + 90075317.

It is an arithmetic number, because the mean of its divisors is an integer number (390326339).

Almost surely, 2^1621355553 is an apocalyptic number.

It is an amenable number.

1621355553 is a deficient number, since it is larger than the sum of its proper divisors (720602481).

1621355553 is a wasteful number, since it uses less digits than its factorization.

1621355553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180150623 (or 180150620 counting only the distinct ones).

The product of its digits is 67500, while the sum is 36.

The square root of 1621355553 is about 40266.0595663395. The cubic root of 1621355553 is about 1174.7877819239.

The spelling of 1621355553 in words is "one billion, six hundred twenty-one million, three hundred fifty-five thousand, five hundred fifty-three".