61931561 has 4 divisors (see below), whose sum is σ = 65574612. Its totient is φ = 58288512.

The previous prime is 61931543. The next prime is 61931579. The reversal of 61931561 is 16513916.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (61931543) and next prime (61931579).

It can be written as a sum of positive squares in 2 ways, for example, as 52128400 + 9803161 = 7220^2 + 3131^2 .

It is not a de Polignac number, because 61931561 - 2¹⁴ = 61915177 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61931581) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1821500 + ... + 1821533.

It is an arithmetic number, because the mean of its divisors is an integer number (16393653).

Almost surely, 2^61931561 is an apocalyptic number.

It is an amenable number.

61931561 is a deficient number, since it is larger than the sum of its proper divisors (3643051).

61931561 is a wasteful number, since it uses less digits than its factorization.

61931561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3643050.

The product of its digits is 4860, while the sum is 32.

The square root of 61931561 is about 7869.6607931981. The cubic root of 61931561 is about 395.6434760898.

The spelling of 61931561 in words is "sixty-one million, nine hundred thirty-one thousand, five hundred sixty-one".