20982391609 has 9 divisors (see below), whose sum is σ = 21512728429. Its totient is φ = 20464831840.

The previous prime is 20982391603. The next prime is 20982391621. The reversal of 20982391609 is 90619328902.

The square root of 20982391609 is 144853.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 996349225 + 19986042384 = 31565^2 + 141372^2 .

It is not a de Polignac number, because 20982391609 - 2⁷ = 20982391481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20982391603) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 5937207 + ... + 5940739.

Almost surely, 2^20982391609 is an apocalyptic number.

20982391609 is the 144853-rd square number.

20982391609 is the 72427-th centered octagonal number.

It is an amenable number.

20982391609 is a deficient number, since it is larger than the sum of its proper divisors (530336820).

20982391609 is an frugal number, since it uses more digits than its factorization.

20982391609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7148 (or 3574 counting only the distinct ones).

The product of its (nonzero) digits is 419904, while the sum is 49.

Multiplying 20982391609 by its sum of digits (49), we get a square (1028137188841 = 1013971²).

The spelling of 20982391609 in words is "twenty billion, nine hundred eighty-two million, three hundred ninety-one thousand, six hundred nine".