21920985469 has 2 divisors, whose sum is σ = 21920985470. Its totient is φ = 21920985468.

The previous prime is 21920985433. The next prime is 21920985473. The reversal of 21920985469 is 96458902912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21915249444 + 5736025 = 148038^2 + 2395^2 .

It is a cyclic number.

It is not a de Polignac number, because 21920985469 - 2²⁵ = 21887431037 is a prime.

It is a super-2 number, since 2×21920985469² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21920989469) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10960492734 + 10960492735.

It is an arithmetic number, because the mean of its divisors is an integer number (10960492735).

Almost surely, 2^21920985469 is an apocalyptic number.

It is an amenable number.

21920985469 is a deficient number, since it is larger than the sum of its proper divisors (1).

21920985469 is an equidigital number, since it uses as much as digits as its factorization.

21920985469 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2799360, while the sum is 55.

The spelling of 21920985469 in words is "twenty-one billion, nine hundred twenty million, nine hundred eighty-five thousand, four hundred sixty-nine".