1621332161 has 4 divisors (see below), whose sum is σ = 1625500500. Its totient is φ = 1617163824.

The previous prime is 1621332151. The next prime is 1621332173. The reversal of 1621332161 is 1612331261.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 226683136 + 1394649025 = 15056^2 + 37345^2 .

It is a cyclic number.

It is not a de Polignac number, because 1621332161 - 2²² = 1617137857 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 1621332161.

It is not an unprimeable number, because it can be changed into a prime (1621332151) 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 3 ways as a sum of consecutive naturals, for example, 2083586 + ... + 2084363.

It is an arithmetic number, because the mean of its divisors is an integer number (406375125).

Almost surely, 2^1621332161 is an apocalyptic number.

It is an amenable number.

1621332161 is a deficient number, since it is larger than the sum of its proper divisors (4168339).

1621332161 is an equidigital number, since it uses as much as digits as its factorization.

1621332161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4168338.

The product of its digits is 1296, while the sum is 26.

The square root of 1621332161 is about 40265.7690973363. The cubic root of 1621332161 is about 1174.7821321723.

The spelling of 1621332161 in words is "one billion, six hundred twenty-one million, three hundred thirty-two thousand, one hundred sixty-one".