1551661663 has 2 divisors, whose sum is σ = 1551661664. Its totient is φ = 1551661662.

The previous prime is 1551661651. The next prime is 1551661681. The reversal of 1551661663 is 3661661551.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1551661663 - 2⁹ = 1551661151 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1551661603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 775830831 + 775830832.

It is an arithmetic number, because the mean of its divisors is an integer number (775830832).

Almost surely, 2^1551661663 is an apocalyptic number.

1551661663 is a deficient number, since it is larger than the sum of its proper divisors (1).

1551661663 is an equidigital number, since it uses as much as digits as its factorization.

1551661663 is an evil number, because the sum of its binary digits is even.

The product of its digits is 97200, while the sum is 40.

The square root of 1551661663 is about 39391.1368584356. The cubic root of 1551661663 is about 1157.7079351586.

The spelling of 1551661663 in words is "one billion, five hundred fifty-one million, six hundred sixty-one thousand, six hundred sixty-three".