20806693152221 has 4 divisors (see below), whose sum is σ = 20807793065052. Its totient is φ = 20805593239392.

The previous prime is 20806693152211. The next prime is 20806693152233. The reversal of 20806693152221 is 12225139660802.

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 14236955229721 + 6569737922500 = 3773189^2 + 2563150^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20806693152221 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 (20806693152211) 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, 549928040 + ... + 549965873.

It is an arithmetic number, because the mean of its divisors is an integer number (5201948266263).

Almost surely, 2^{20806693152221} is an apocalyptic number.

It is an amenable number.

20806693152221 is a deficient number, since it is larger than the sum of its proper divisors (1099912831).

20806693152221 is a wasteful number, since it uses less digits than its factorization.

20806693152221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1099912830.

The product of its (nonzero) digits is 622080, while the sum is 47.

The spelling of 20806693152221 in words is "twenty trillion, eight hundred six billion, six hundred ninety-three million, one hundred fifty-two thousand, two hundred twenty-one".