1620104621 has 4 divisors (see below), whose sum is σ = 1620534432. Its totient is φ = 1619674812.

The previous prime is 1620104579. The next prime is 1620104669. The reversal of 1620104621 is 1264010261.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1264010261 = 139 ⋅9093599.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1620104621 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1620104021) 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, 209201 + ... + 216806.

It is an arithmetic number, because the mean of its divisors is an integer number (405133608).

Almost surely, 2^1620104621 is an apocalyptic number.

It is an amenable number.

1620104621 is a deficient number, since it is larger than the sum of its proper divisors (429811).

1620104621 is an equidigital number, since it uses as much as digits as its factorization.

1620104621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 429810.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 1620104621 is about 40250.5232388350. The cubic root of 1620104621 is about 1174.4855743600.

Adding to 1620104621 its reverse (1264010261), we get a palindrome (2884114882).

The spelling of 1620104621 in words is "one billion, six hundred twenty million, one hundred four thousand, six hundred twenty-one".