21098015797 has 2 divisors, whose sum is σ = 21098015798. Its totient is φ = 21098015796.

The previous prime is 21098015779. The next prime is 21098015831. The reversal of 21098015797 is 79751089012.

Together with previous prime (21098015779) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14319951556 + 6778064241 = 119666^2 + 82329^2 .

It is a cyclic number.

It is not a de Polignac number, because 21098015797 - 2⁷ = 21098015669 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21098015797.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21098012797) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10549007898 + 10549007899.

It is an arithmetic number, because the mean of its divisors is an integer number (10549007899).

Almost surely, 2^21098015797 is an apocalyptic number.

It is an amenable number.

21098015797 is a deficient number, since it is larger than the sum of its proper divisors (1).

21098015797 is an equidigital number, since it uses as much as digits as its factorization.

21098015797 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 317520, while the sum is 49.

The spelling of 21098015797 in words is "twenty-one billion, ninety-eight million, fifteen thousand, seven hundred ninety-seven".