21798428957 has 2 divisors, whose sum is σ = 21798428958. Its totient is φ = 21798428956.

The previous prime is 21798428941. The next prime is 21798429089. The reversal of 21798428957 is 75982489712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16176278596 + 5622150361 = 127186^2 + 74981^2 .

It is a cyclic number.

It is not a de Polignac number, because 21798428957 - 2⁴ = 21798428941 is a prime.

It is a super-2 number, since 2×21798428957² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21798428957.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21798424957) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10899214478 + 10899214479.

It is an arithmetic number, because the mean of its divisors is an integer number (10899214479).

Almost surely, 2^21798428957 is an apocalyptic number.

It is an amenable number.

21798428957 is a deficient number, since it is larger than the sum of its proper divisors (1).

21798428957 is an equidigital number, since it uses as much as digits as its factorization.

21798428957 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20321280, while the sum is 62.

The spelling of 21798428957 in words is "twenty-one billion, seven hundred ninety-eight million, four hundred twenty-eight thousand, nine hundred fifty-seven".