61931509 has 4 divisors (see below), whose sum is σ = 61947340. Its totient is φ = 61915680.

The previous prime is 61931491. The next prime is 61931537. The reversal of 61931509 is 90513916.

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 can be written as a sum of positive squares in 2 ways, for example, as 12229009 + 49702500 = 3497^2 + 7050^2 .

It is a cyclic number.

It is not a de Polignac number, because 61931509 - 2⁷ = 61931381 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61931539) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2689 + ... + 11449.

It is an arithmetic number, because the mean of its divisors is an integer number (15486835).

Almost surely, 2^61931509 is an apocalyptic number.

It is an amenable number.

61931509 is a deficient number, since it is larger than the sum of its proper divisors (15831).

61931509 is an equidigital number, since it uses as much as digits as its factorization.

61931509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15830.

The product of its (nonzero) digits is 7290, while the sum is 34.

The square root of 61931509 is about 7869.6574893702. The cubic root of 61931509 is about 395.6433653575.

The spelling of 61931509 in words is "sixty-one million, nine hundred thirty-one thousand, five hundred nine".