20745721473 has 4 divisors (see below), whose sum is σ = 27660961968. Its totient is φ = 13830480980.

The previous prime is 20745721441. The next prime is 20745721481. The reversal of 20745721473 is 37412754702.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20745721473 - 2⁵ = 20745721441 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20745721573) 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, 3457620243 + ... + 3457620248.

It is an arithmetic number, because the mean of its divisors is an integer number (6915240492).

Almost surely, 2^20745721473 is an apocalyptic number.

It is an amenable number.

20745721473 is a deficient number, since it is larger than the sum of its proper divisors (6915240495).

20745721473 is an equidigital number, since it uses as much as digits as its factorization.

20745721473 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6915240494.

The product of its (nonzero) digits is 329280, while the sum is 42.

The spelling of 20745721473 in words is "twenty billion, seven hundred forty-five million, seven hundred twenty-one thousand, four hundred seventy-three".