1661653291 has 2 divisors, whose sum is σ = 1661653292. Its totient is φ = 1661653290.

The previous prime is 1661653271. The next prime is 1661653309. The reversal of 1661653291 is 1923561661.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1661653291 - 2¹⁵ = 1661620523 is a prime.

It is a super-2 number, since 2×1661653291² = 5522183318982261362, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1661653271) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 830826645 + 830826646.

It is an arithmetic number, because the mean of its divisors is an integer number (830826646).

Almost surely, 2^1661653291 is an apocalyptic number.

1661653291 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661653291 is an equidigital number, since it uses as much as digits as its factorization.

1661653291 is an evil number, because the sum of its binary digits is even.

The product of its digits is 58320, while the sum is 40.

The square root of 1661653291 is about 40763.3817414601. The cubic root of 1661653291 is about 1184.4411046949.

The spelling of 1661653291 in words is "one billion, six hundred sixty-one million, six hundred fifty-three thousand, two hundred ninety-one".