1605866551 has 2 divisors, whose sum is σ = 1605866552. Its totient is φ = 1605866550.

The previous prime is 1605866539. The next prime is 1605866611. The reversal of 1605866551 is 1556685061.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1605866551 - 2¹⁷ = 1605735479 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1605866498 and 1605866507.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1605866501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 802933275 + 802933276.

It is an arithmetic number, because the mean of its divisors is an integer number (802933276).

Almost surely, 2^1605866551 is an apocalyptic number.

1605866551 is a deficient number, since it is larger than the sum of its proper divisors (1).

1605866551 is an equidigital number, since it uses as much as digits as its factorization.

1605866551 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216000, while the sum is 43.

The square root of 1605866551 is about 40073.2647908802. The cubic root of 1605866551 is about 1171.0348433122.

The spelling of 1605866551 in words is "one billion, six hundred five million, eight hundred sixty-six thousand, five hundred fifty-one".