217920406469 has 2 divisors, whose sum is σ = 217920406470. Its totient is φ = 217920406468.

The previous prime is 217920406423. The next prime is 217920406511. The reversal of 217920406469 is 964604029712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 175298803969 + 42621602500 = 418687^2 + 206450^2 .

It is a cyclic number.

It is not a de Polignac number, because 217920406469 - 2¹⁶ = 217920340933 is a prime.

It is a super-2 number, since 2×217920406469² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217920406169) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108960203234 + 108960203235.

It is an arithmetic number, because the mean of its divisors is an integer number (108960203235).

Almost surely, 2^217920406469 is an apocalyptic number.

It is an amenable number.

217920406469 is a deficient number, since it is larger than the sum of its proper divisors (1).

217920406469 is an equidigital number, since it uses as much as digits as its factorization.

217920406469 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1306368, while the sum is 50.

The spelling of 217920406469 in words is "two hundred seventeen billion, nine hundred twenty million, four hundred six thousand, four hundred sixty-nine".