1621432213 has 2 divisors, whose sum is σ = 1621432214. Its totient is φ = 1621432212.

The previous prime is 1621432177. The next prime is 1621432229. The reversal of 1621432213 is 3122341261.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 905227569 + 716204644 = 30087^2 + 26762^2 .

It is a cyclic number.

It is not a de Polignac number, because 1621432213 - 2⁹ = 1621431701 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1621432313) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 810716106 + 810716107.

It is an arithmetic number, because the mean of its divisors is an integer number (810716107).

Almost surely, 2^1621432213 is an apocalyptic number.

It is an amenable number.

1621432213 is a deficient number, since it is larger than the sum of its proper divisors (1).

1621432213 is an equidigital number, since it uses as much as digits as its factorization.

1621432213 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1728, while the sum is 25.

The square root of 1621432213 is about 40267.0114734133. The cubic root of 1621432213 is about 1174.8062968453.

Adding to 1621432213 its reverse (3122341261), we get a palindrome (4743773474).

The spelling of 1621432213 in words is "one billion, six hundred twenty-one million, four hundred thirty-two thousand, two hundred thirteen".