155203693681 has 9 divisors (see below), whose sum is σ = 156298246923. Its totient is φ = 154116760800.

The previous prime is 155203693657. The next prime is 155203693717. The reversal of 155203693681 is 186396302551.

It is a happy number.

The square root of 155203693681 is 393959.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 74615839281 + 80587854400 = 273159^2 + 283880^2 .

It is not a de Polignac number, because 155203693681 - 2⁵ = 155203693649 is a prime.

It is a super-2 number, since 2×155203693681² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (155203691681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 59486505 + ... + 59489113.

Almost surely, 2^155203693681 is an apocalyptic number.

155203693681 is the 393959-th square number.

155203693681 is the 196980-th centered octagonal number.

It is an amenable number.

155203693681 is a deficient number, since it is larger than the sum of its proper divisors (1094553242).

155203693681 is an frugal number, since it uses more digits than its factorization.

155203693681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5520 (or 2760 counting only the distinct ones).

The product of its (nonzero) digits is 1166400, while the sum is 49.

Multiplying 155203693681 by its sum of digits (49), we get a square (7604980990369 = 2757713²).

The spelling of 155203693681 in words is "one hundred fifty-five billion, two hundred three million, six hundred ninety-three thousand, six hundred eighty-one".