1616566381 has 4 divisors (see below), whose sum is σ = 1654160992. Its totient is φ = 1578971772.

The previous prime is 1616566373. The next prime is 1616566403. The reversal of 1616566381 is 1836656161.

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.

It is a cyclic number.

It is not a de Polignac number, because 1616566381 - 2³ = 1616566373 is a prime.

It is a super-2 number, since 2×1616566381² = 5226573728358874322, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (43), and also a Moran number because the ratio is a prime number: 37594567 = 1616566381 / (1 + 6 + 1 + 6 + 5 + 6 + 6 + 3 + 8 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1616566321) 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, 18797241 + ... + 18797326.

It is an arithmetic number, because the mean of its divisors is an integer number (413540248).

Almost surely, 2^1616566381 is an apocalyptic number.

It is an amenable number.

1616566381 is a deficient number, since it is larger than the sum of its proper divisors (37594611).

1616566381 is an equidigital number, since it uses as much as digits as its factorization.

1616566381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37594610.

The product of its digits is 155520, while the sum is 43.

The square root of 1616566381 is about 40206.5464943210. The cubic root of 1616566381 is about 1173.6299422221.

The spelling of 1616566381 in words is "one billion, six hundred sixteen million, five hundred sixty-six thousand, three hundred eighty-one".