20768913421 has 2 divisors, whose sum is σ = 20768913422. Its totient is φ = 20768913420.

The previous prime is 20768913391. The next prime is 20768913437. The reversal of 20768913421 is 12431986702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18492192196 + 2276721225 = 135986^2 + 47715^2 .

It is a cyclic number.

It is not a de Polignac number, because 20768913421 - 2¹³ = 20768905229 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20768913721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10384456710 + 10384456711.

It is an arithmetic number, because the mean of its divisors is an integer number (10384456711).

Almost surely, 2^20768913421 is an apocalyptic number.

It is an amenable number.

20768913421 is a deficient number, since it is larger than the sum of its proper divisors (1).

20768913421 is an equidigital number, since it uses as much as digits as its factorization.

20768913421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 145152, while the sum is 43.

The spelling of 20768913421 in words is "twenty billion, seven hundred sixty-eight million, nine hundred thirteen thousand, four hundred twenty-one".