61756509477961 has 9 divisors (see below), whose sum is σ = 63813169429479. Its totient is φ = 59764128255000.

The previous prime is 61756509477953. The next prime is 61756509477997. The reversal of 61756509477961 is 16977490565716.

The square root of 61756509477961 is 7858531.

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

It can be written as a sum of positive squares in only one way, i.e., 59344389867961 + 2412119610000 = 7703531^2 + 1553100^2 .

It is not a de Polignac number, because 61756509477961 - 2³ = 61756509477953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61756509477911) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 243487711 + ... + 243741211.

It is an arithmetic number, because the mean of its divisors is an integer number (7090352158831).

Almost surely, 2^{61756509477961} is an apocalyptic number.

61756509477961 is the 7858531-st square number.

61756509477961 is the 3929266-th centered octagonal number.

It is an amenable number.

61756509477961 is a deficient number, since it is larger than the sum of its proper divisors (2056659951518).

61756509477961 is an frugal number, since it uses more digits than its factorization.

61756509477961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 507064 (or 253532 counting only the distinct ones).

The product of its (nonzero) digits is 600112800, while the sum is 73.

The spelling of 61756509477961 in words is "sixty-one trillion, seven hundred fifty-six billion, five hundred nine million, four hundred seventy-seven thousand, nine hundred sixty-one".