1661155511 has 2 divisors, whose sum is σ = 1661155512. Its totient is φ = 1661155510.

The previous prime is 1661155499. The next prime is 1661155523. The reversal of 1661155511 is 1155511661.

It is a balanced prime because it is at equal distance from previous prime (1661155499) and next prime (1661155523).

It is a cyclic number.

It is not a de Polignac number, because 1661155511 - 2¹⁴ = 1661139127 is a prime.

It is a super-2 number, since 2×1661155511² = 5518875263451342242, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1661155591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 830577755 + 830577756.

It is an arithmetic number, because the mean of its divisors is an integer number (830577756).

Almost surely, 2^1661155511 is an apocalyptic number.

1661155511 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661155511 is an equidigital number, since it uses as much as digits as its factorization.

1661155511 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4500, while the sum is 32.

The square root of 1661155511 is about 40757.2755590950. The cubic root of 1661155511 is about 1184.3228188928.

The spelling of 1661155511 in words is "one billion, six hundred sixty-one million, one hundred fifty-five thousand, five hundred eleven".