1566217649 has 2 divisors, whose sum is σ = 1566217650. Its totient is φ = 1566217648.

The previous prime is 1566217607. The next prime is 1566217651. The reversal of 1566217649 is 9467126651.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1459240000 + 106977649 = 38200^2 + 10343^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1566217649 is a prime.

Together with 1566217651, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1566217699) 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, 783108824 + 783108825.

It is an arithmetic number, because the mean of its divisors is an integer number (783108825).

Almost surely, 2^1566217649 is an apocalyptic number.

It is an amenable number.

1566217649 is a deficient number, since it is larger than the sum of its proper divisors (1).

1566217649 is an equidigital number, since it uses as much as digits as its factorization.

1566217649 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 544320, while the sum is 47.

The square root of 1566217649 is about 39575.4677672924. The cubic root of 1566217649 is about 1161.3167887019.

It can be divided in two parts, 15 and 66217649, that multiplied together give a triangular number (993264735 = T₄₄₅₇₀).

The spelling of 1566217649 in words is "one billion, five hundred sixty-six million, two hundred seventeen thousand, six hundred forty-nine".