1661406837 has 4 divisors (see below), whose sum is σ = 2215209120. Its totient is φ = 1107604556.

The previous prime is 1661406833. The next prime is 1661406907. The reversal of 1661406837 is 7386041661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 7386041661 = 3 ⋅2462013887.

It is a cyclic number.

It is not a de Polignac number, because 1661406837 - 2² = 1661406833 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661406833) 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, 276901137 + ... + 276901142.

It is an arithmetic number, because the mean of its divisors is an integer number (553802280).

Almost surely, 2^1661406837 is an apocalyptic number.

It is an amenable number.

1661406837 is a deficient number, since it is larger than the sum of its proper divisors (553802283).

1661406837 is an equidigital number, since it uses as much as digits as its factorization.

1661406837 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 553802282.

The product of its (nonzero) digits is 145152, while the sum is 42.

The square root of 1661406837 is about 40760.3586466066. The cubic root of 1661406837 is about 1184.3825436055.

It can be divided in two parts, 166 and 1406837, that added together give a triangular number (1407003 = T₁₆₇₇).

The spelling of 1661406837 in words is "one billion, six hundred sixty-one million, four hundred six thousand, eight hundred thirty-seven".