61815 has 16 divisors (see below), whose sum is σ = 106848. Its totient is φ = 30336.

The previous prime is 61813. The next prime is 61819. The reversal of 61815 is 51816.

It is not a de Polignac number, because 61815 - 2¹ = 61813 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 61791 and 61800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 37 + ... + 353.

It is an arithmetic number, because the mean of its divisors is an integer number (6678).

2⁶¹⁸¹⁵ is an apocalyptic number.

61815 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

61815 is a deficient number, since it is larger than the sum of its proper divisors (45033).

61815 is a wasteful number, since it uses less digits than its factorization.

61815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 338.

The product of its digits is 240, while the sum is 21.

The square root of 61815 is about 248.6262254872. The cubic root of 61815 is about 39.5395107511.

Subtracting from 61815 its reverse (51816), we obtain a palindrome (9999).

The spelling of 61815 in words is "sixty-one thousand, eight hundred fifteen".