20990919100421 has 2 divisors, whose sum is σ = 20990919100422. Its totient is φ = 20990919100420.

The previous prime is 20990919100387. The next prime is 20990919100427. The reversal of 20990919100421 is 12400191909902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16598901930625 + 4392017169796 = 4074175^2 + 2095714^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20990919100421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20990919100427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10495459550210 + 10495459550211.

It is an arithmetic number, because the mean of its divisors is an integer number (10495459550211).

Almost surely, 2^{20990919100421} is an apocalyptic number.

It is an amenable number.

20990919100421 is a deficient number, since it is larger than the sum of its proper divisors (1).

20990919100421 is an equidigital number, since it uses as much as digits as its factorization.

20990919100421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 104976, while the sum is 47.

The spelling of 20990919100421 in words is "twenty trillion, nine hundred ninety billion, nine hundred nineteen million, one hundred thousand, four hundred twenty-one".