1661682397 has 4 divisors (see below), whose sum is σ = 1718981820. Its totient is φ = 1604382976.

The previous prime is 1661682389. The next prime is 1661682409. The reversal of 1661682397 is 7932861661.

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

It can be written as a sum of positive squares in 2 ways, for example, as 907575876 + 754106521 = 30126^2 + 27461^2 .

It is a cyclic number.

It is not a de Polignac number, because 1661682397 - 2³ = 1661682389 is a prime.

It is a super-2 number, since 2×1661682397² = 5522376776999331218, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1661682397.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661682307) 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, 28649668 + ... + 28649725.

It is an arithmetic number, because the mean of its divisors is an integer number (429745455).

Almost surely, 2^1661682397 is an apocalyptic number.

It is an amenable number.

1661682397 is a deficient number, since it is larger than the sum of its proper divisors (57299423).

1661682397 is an equidigital number, since it uses as much as digits as its factorization.

1661682397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57299422.

The product of its digits is 653184, while the sum is 49.

The square root of 1661682397 is about 40763.7387514933. The cubic root of 1661682397 is about 1184.4480203256.

The spelling of 1661682397 in words is "one billion, six hundred sixty-one million, six hundred eighty-two thousand, three hundred ninety-seven".