1661645019 has 16 divisors (see below), whose sum is σ = 2333566080. Its totient is φ = 1048815360.

The previous prime is 1661644993. The next prime is 1661645047. The reversal of 1661645019 is 9105461661.

It is not a de Polignac number, because 1661645019 - 2⁸ = 1661644763 is a prime.

It is a super-2 number, since 2×1661645019² = 5522128338335020722, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1661645819) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 95179 + ... + 111275.

It is an arithmetic number, because the mean of its divisors is an integer number (145847880).

Almost surely, 2^1661645019 is an apocalyptic number.

1661645019 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

1661645019 is a deficient number, since it is larger than the sum of its proper divisors (671921061).

1661645019 is a wasteful number, since it uses less digits than its factorization.

1661645019 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17930.

The product of its (nonzero) digits is 38880, while the sum is 39.

The square root of 1661645019 is about 40763.2802777205. The cubic root of 1661645019 is about 1184.4391392402.

The spelling of 1661645019 in words is "one billion, six hundred sixty-one million, six hundred forty-five thousand, nineteen".