20708455681 has 4 divisors (see below), whose sum is σ = 20709902164. Its totient is φ = 20707009200.

The previous prime is 20708455631. The next prime is 20708455717. The reversal of 20708455681 is 18655480702.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7635963456 + 13072492225 = 87384^2 + 114335^2 .

It is a cyclic number.

It is not a de Polignac number, because 20708455681 - 2⁷ = 20708455553 is a prime.

It is a super-2 number, since 2×20708455681² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20708455631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 701550 + ... + 730471.

It is an arithmetic number, because the mean of its divisors is an integer number (5177475541).

Almost surely, 2^20708455681 is an apocalyptic number.

It is an amenable number.

20708455681 is a deficient number, since it is larger than the sum of its proper divisors (1446483).

20708455681 is a wasteful number, since it uses less digits than its factorization.

20708455681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1446482.

The product of its (nonzero) digits is 537600, while the sum is 46.

The spelling of 20708455681 in words is "twenty billion, seven hundred eight million, four hundred fifty-five thousand, six hundred eighty-one".