20954657309 has 4 divisors (see below), whose sum is σ = 20955357660. Its totient is φ = 20953956960.

The previous prime is 20954657287. The next prime is 20954657327. The reversal of 20954657309 is 90375645902.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90375645902 = 2 ⋅45187822951.

It can be written as a sum of positive squares in 2 ways, for example, as 4743765625 + 16210891684 = 68875^2 + 127322^2 .

It is a cyclic number.

It is not a de Polignac number, because 20954657309 - 2¹⁶ = 20954591773 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20954650309) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 303194 + ... + 365835.

It is an arithmetic number, because the mean of its divisors is an integer number (5238839415).

Almost surely, 2^20954657309 is an apocalyptic number.

It is an amenable number.

20954657309 is a deficient number, since it is larger than the sum of its proper divisors (700351).

20954657309 is an equidigital number, since it uses as much as digits as its factorization.

20954657309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 700350.

The product of its (nonzero) digits is 2041200, while the sum is 50.

The spelling of 20954657309 in words is "twenty billion, nine hundred fifty-four million, six hundred fifty-seven thousand, three hundred nine".