20545571772421 has 4 divisors (see below), whose sum is σ = 21626917655200. Its totient is φ = 19464225889644.

The previous prime is 20545571772413. The next prime is 20545571772431. The reversal of 20545571772421 is 12427717554502.

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 20545571772421 - 2³ = 20545571772413 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 (20545571772431) 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, 540672941361 + ... + 540672941398.

It is an arithmetic number, because the mean of its divisors is an integer number (5406729413800).

Almost surely, 2^{20545571772421} is an apocalyptic number.

It is an amenable number.

20545571772421 is a deficient number, since it is larger than the sum of its proper divisors (1081345882779).

20545571772421 is a wasteful number, since it uses less digits than its factorization.

20545571772421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1081345882778.

The product of its (nonzero) digits is 5488000, while the sum is 52.

The spelling of 20545571772421 in words is "twenty trillion, five hundred forty-five billion, five hundred seventy-one million, seven hundred seventy-two thousand, four hundred twenty-one".