1661155651 has 2 divisors, whose sum is σ = 1661155652. Its totient is φ = 1661155650.

The previous prime is 1661155597. The next prime is 1661155669. The reversal of 1661155651 is 1565511661.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1661155651 - 2⁷ = 1661155523 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1661155651.

It is not a weakly prime, because it can be changed into another prime (1661155751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 830577825 + 830577826.

It is an arithmetic number, because the mean of its divisors is an integer number (830577826).

Almost surely, 2^1661155651 is an apocalyptic number.

1661155651 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661155651 is an equidigital number, since it uses as much as digits as its factorization.

1661155651 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 27000, while the sum is 37.

The square root of 1661155651 is about 40757.2772765797. The cubic root of 1661155651 is about 1184.3228521638.

The spelling of 1661155651 in words is "one billion, six hundred sixty-one million, one hundred fifty-five thousand, six hundred fifty-one".