1621639314509 has 2 divisors, whose sum is σ = 1621639314510. Its totient is φ = 1621639314508.

The previous prime is 1621639314403. The next prime is 1621639314539. The reversal of 1621639314509 is 9054139361261.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1559134314409 + 62505000100 = 1248653^2 + 250010^2 .

It is a cyclic number.

It is not a de Polignac number, because 1621639314509 - 2¹⁶ = 1621639248973 is a prime.

It is a super-2 number, since 2×1621639314509² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1621639314539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 810819657254 + 810819657255.

It is an arithmetic number, because the mean of its divisors is an integer number (810819657255).

Almost surely, 2^{1621639314509} is an apocalyptic number.

It is an amenable number.

1621639314509 is a deficient number, since it is larger than the sum of its proper divisors (1).

1621639314509 is an equidigital number, since it uses as much as digits as its factorization.

1621639314509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1049760, while the sum is 50.

The spelling of 1621639314509 in words is "one trillion, six hundred twenty-one billion, six hundred thirty-nine million, three hundred fourteen thousand, five hundred nine".