61815385129 has 3 divisors (see below), whose sum is σ = 61815633757. Its totient is φ = 61815136502.

The previous prime is 61815385127. The next prime is 61815385153. The reversal of 61815385129 is 92158351816.

The square root of 61815385129 is 248627.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 61815385129 - 2¹ = 61815385127 is a prime.

It is a super-2 number, since 2×61815385129² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61815385123) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 124314 + ... + 372940.

Almost surely, 2^61815385129 is an apocalyptic number.

61815385129 is the 248627-th square number.

61815385129 is the 124314-th centered octagonal number.

It is an amenable number.

61815385129 is a deficient number, since it is larger than the sum of its proper divisors (248628).

61815385129 is an frugal number, since it uses more digits than its factorization.

61815385129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 497254 (or 248627 counting only the distinct ones).

The product of its digits is 518400, while the sum is 49.

Multiplying 61815385129 by its sum of digits (49), we get a square (3028953871321 = 1740389²).

The spelling of 61815385129 in words is "sixty-one billion, eight hundred fifteen million, three hundred eighty-five thousand, one hundred twenty-nine".