21019020497 has 2 divisors, whose sum is σ = 21019020498. Its totient is φ = 21019020496.

The previous prime is 21019020437. The next prime is 21019020563. The reversal of 21019020497 is 79402091012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20339323456 + 679697041 = 142616^2 + 26071^2 .

It is a cyclic number.

It is not a de Polignac number, because 21019020497 - 2²⁴ = 21002243281 is a prime.

It is a super-2 number, since 2×21019020497² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21019020437) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10509510248 + 10509510249.

It is an arithmetic number, because the mean of its divisors is an integer number (10509510249).

Almost surely, 2^21019020497 is an apocalyptic number.

It is an amenable number.

21019020497 is a deficient number, since it is larger than the sum of its proper divisors (1).

21019020497 is an equidigital number, since it uses as much as digits as its factorization.

21019020497 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9072, while the sum is 35.

The spelling of 21019020497 in words is "twenty-one billion, nineteen million, twenty thousand, four hundred ninety-seven".