1556233661 has 4 divisors (see below), whose sum is σ = 1556416992. Its totient is φ = 1556050332.

The previous prime is 1556233643. The next prime is 1556233673. The reversal of 1556233661 is 1663326551.

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 1556233661 - 2¹⁴ = 1556217277 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1556233621) 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, 78281 + ... + 96126.

It is an arithmetic number, because the mean of its divisors is an integer number (389104248).

Almost surely, 2^1556233661 is an apocalyptic number.

It is an amenable number.

1556233661 is a deficient number, since it is larger than the sum of its proper divisors (183331).

1556233661 is an equidigital number, since it uses as much as digits as its factorization.

1556233661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 183330.

The product of its digits is 97200, while the sum is 38.

The square root of 1556233661 is about 39449.1275061946. The cubic root of 1556233661 is about 1158.8438890218.

The spelling of 1556233661 in words is "one billion, five hundred fifty-six million, two hundred thirty-three thousand, six hundred sixty-one".