1621221523 has 2 divisors, whose sum is σ = 1621221524. Its totient is φ = 1621221522.

The previous prime is 1621221443. The next prime is 1621221527. The reversal of 1621221523 is 3251221261.

It is a strong prime.

It is an emirp because it is prime and its reverse (3251221261) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1621221523 - 2¹³ = 1621213331 is a prime.

It is not a weakly prime, because it can be changed into another prime (1621221527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 810610761 + 810610762.

It is an arithmetic number, because the mean of its divisors is an integer number (810610762).

Almost surely, 2^1621221523 is an apocalyptic number.

1621221523 is a deficient number, since it is larger than the sum of its proper divisors (1).

1621221523 is an equidigital number, since it uses as much as digits as its factorization.

1621221523 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1440, while the sum is 25.

The square root of 1621221523 is about 40264.3952270489. The cubic root of 1621221523 is about 1174.7554095991.

Adding to 1621221523 its reverse (3251221261), we get a palindrome (4872442784).

The spelling of 1621221523 in words is "one billion, six hundred twenty-one million, two hundred twenty-one thousand, five hundred twenty-three".