1665566551 has 48 divisors (see below), whose sum is σ = 2042560800. Its totient is φ = 1341992960.

The previous prime is 1665566549. The next prime is 1665566563. The reversal of 1665566551 is 1556655661.

It is not a de Polignac number, because 1665566551 - 2¹ = 1665566549 is a prime.

It is a super-2 number, since 2×1665566551² = 5548223871620071202, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665566531) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 11178225 + ... + 11178373.

It is an arithmetic number, because the mean of its divisors is an integer number (42553350).

Almost surely, 2^1665566551 is an apocalyptic number.

1665566551 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1665566551 is a deficient number, since it is larger than the sum of its proper divisors (376994249).

1665566551 is a wasteful number, since it uses less digits than its factorization.

1665566551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 336 (or 313 counting only the distinct ones).

The product of its digits is 810000, while the sum is 46.

The square root of 1665566551 is about 40811.3532120659. The cubic root of 1665566551 is about 1185.3701778091.

The spelling of 1665566551 in words is "one billion, six hundred sixty-five million, five hundred sixty-six thousand, five hundred fifty-one".