1661293615 has 4 divisors (see below), whose sum is σ = 1993552344. Its totient is φ = 1329034888.

The previous prime is 1661293577. The next prime is 1661293619. The reversal of 1661293615 is 5163921661.

It is a happy number.

1661293615 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1661293615 - 2⁹ = 1661293103 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661293619) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 166129357 + ... + 166129366.

It is an arithmetic number, because the mean of its divisors is an integer number (498388086).

Almost surely, 2^1661293615 is an apocalyptic number.

1661293615 is a deficient number, since it is larger than the sum of its proper divisors (332258729).

1661293615 is an equidigital number, since it uses as much as digits as its factorization.

1661293615 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332258728.

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

The square root of 1661293615 is about 40758.9697490013. The cubic root of 1661293615 is about 1184.3556384542.

It can be divided in two parts, 166129 and 3615, that added together give a square (169744 = 412²).

The spelling of 1661293615 in words is "one billion, six hundred sixty-one million, two hundred ninety-three thousand, six hundred fifteen".