156781661 has 4 divisors (see below), whose sum is σ = 157044000. Its totient is φ = 156519324.

The previous prime is 156781637. The next prime is 156781693. The reversal of 156781661 is 166187651.

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: 166187651 = 7 ⋅23741093.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-156781661 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 (156781621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 130271 + ... + 131468.

It is an arithmetic number, because the mean of its divisors is an integer number (39261000).

Almost surely, 2^156781661 is an apocalyptic number.

It is an amenable number.

156781661 is a deficient number, since it is larger than the sum of its proper divisors (262339).

156781661 is an equidigital number, since it uses as much as digits as its factorization.

156781661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 262338.

The product of its digits is 60480, while the sum is 41.

The square root of 156781661 is about 12521.2483802535. The cubic root of 156781661 is about 539.2188763453.

The spelling of 156781661 in words is "one hundred fifty-six million, seven hundred eighty-one thousand, six hundred sixty-one".