31017447787561 has 9 divisors (see below), whose sum is σ = 31264315679991. Its totient is φ = 30772514179512.

The previous prime is 31017447787549. The next prime is 31017447787589. The reversal of 31017447787561 is 16578774471013.

It is a happy number.

The square root of 31017447787561 is 5569331.

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., 4131605043225 + 26885842744336 = 2032635^2 + 5185156^2 .

It is not a de Polignac number, because 31017447787561 - 2⁹ = 31017447787049 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 31017447787561.

It is not an unprimeable number, because it can be changed into a prime (31017447787661) 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, 707283111 + ... + 707326963.

Almost surely, 2^{31017447787561} is an apocalyptic number.

31017447787561 is the 5569331-st square number.

31017447787561 is the 2784666-th centered octagonal number.

It is an amenable number.

31017447787561 is a deficient number, since it is larger than the sum of its proper divisors (246867892430).

31017447787561 is an frugal number, since it uses more digits than its factorization.

31017447787561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87960 (or 43980 counting only the distinct ones).

The product of its (nonzero) digits is 27659520, while the sum is 61.

The spelling of 31017447787561 in words is "thirty-one trillion, seventeen billion, four hundred forty-seven million, seven hundred eighty-seven thousand, five hundred sixty-one".