1621004201 has 4 divisors (see below), whose sum is σ = 1643209812. Its totient is φ = 1598798592.

The previous prime is 1621004191. The next prime is 1621004233. The reversal of 1621004201 is 1024001261.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1024001261 = 10559 ⋅96979.

It can be written as a sum of positive squares in 2 ways, for example, as 543589225 + 1077414976 = 23315^2 + 32824^2 .

It is a cyclic number.

It is not a de Polignac number, because 1621004201 - 2¹⁴ = 1620987817 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 1621004201.

It is not an unprimeable number, because it can be changed into a prime (1621004101) 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, 11102696 + ... + 11102841.

It is an arithmetic number, because the mean of its divisors is an integer number (410802453).

Almost surely, 2^1621004201 is an apocalyptic number.

It is an amenable number.

1621004201 is a deficient number, since it is larger than the sum of its proper divisors (22205611).

1621004201 is an equidigital number, since it uses as much as digits as its factorization.

1621004201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22205610.

The product of its (nonzero) digits is 96, while the sum is 17.

The square root of 1621004201 is about 40261.6964496033. The cubic root of 1621004201 is about 1174.7029159290.

Adding to 1621004201 its reverse (1024001261), we get a palindrome (2645005462).

The spelling of 1621004201 in words is "one billion, six hundred twenty-one million, four thousand, two hundred one".