61815861 has 12 divisors (see below), whose sum is σ = 90974988. Its totient is φ = 40432704.

The previous prime is 61815821. The next prime is 61815877. The reversal of 61815861 is 16851816.

It can be written as a sum of positive squares in 2 ways, for example, as 28291761 + 33524100 = 5319^2 + 5790^2 .

It is a de Polignac number, because none of the positive numbers 2^k-61815861 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61815821) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 64320 + ... + 65273.

It is an arithmetic number, because the mean of its divisors is an integer number (7581249).

Almost surely, 2^61815861 is an apocalyptic number.

It is an amenable number.

61815861 is a deficient number, since it is larger than the sum of its proper divisors (29159127).

61815861 is a wasteful number, since it uses less digits than its factorization.

61815861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129652 (or 129649 counting only the distinct ones).

The product of its digits is 11520, while the sum is 36.

The square root of 61815861 is about 7862.3063410172. The cubic root of 61815861 is about 395.3969432765.

The spelling of 61815861 in words is "sixty-one million, eight hundred fifteen thousand, eight hundred sixty-one".