20980621957 has 2 divisors, whose sum is σ = 20980621958. Its totient is φ = 20980621956.

The previous prime is 20980621951. The next prime is 20980622009. The reversal of 20980621957 is 75912608902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20345884321 + 634737636 = 142639^2 + 25194^2 .

It is a cyclic number.

It is not a de Polignac number, because 20980621957 - 2¹⁹ = 20980097669 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20980621957.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20980621951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10490310978 + 10490310979.

It is an arithmetic number, because the mean of its divisors is an integer number (10490310979).

Almost surely, 2^20980621957 is an apocalyptic number.

It is an amenable number.

20980621957 is a deficient number, since it is larger than the sum of its proper divisors (1).

20980621957 is an equidigital number, since it uses as much as digits as its factorization.

20980621957 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 544320, while the sum is 49.

The spelling of 20980621957 in words is "twenty billion, nine hundred eighty million, six hundred twenty-one thousand, nine hundred fifty-seven".