1621864613 has 2 divisors, whose sum is σ = 1621864614. Its totient is φ = 1621864612.

The previous prime is 1621864609. The next prime is 1621864627. The reversal of 1621864613 is 3164681261.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1545511969 + 76352644 = 39313^2 + 8738^2 .

It is a cyclic number.

It is not a de Polignac number, because 1621864613 - 2² = 1621864609 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1621864693) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 810932306 + 810932307.

It is an arithmetic number, because the mean of its divisors is an integer number (810932307).

Almost surely, 2^1621864613 is an apocalyptic number.

It is an amenable number.

1621864613 is a deficient number, since it is larger than the sum of its proper divisors (1).

1621864613 is an equidigital number, since it uses as much as digits as its factorization.

1621864613 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41472, while the sum is 38.

The square root of 1621864613 is about 40272.3802748236. The cubic root of 1621864613 is about 1174.9107191556.

The spelling of 1621864613 in words is "one billion, six hundred twenty-one million, eight hundred sixty-four thousand, six hundred thirteen".