771561 has 24 divisors (see below), whose sum is σ = 1312064. Its totient is φ = 427680.

The previous prime is 771553. The next prime is 771569. The reversal of 771561 is 165177.

It is an interprime number because it is at equal distance from previous prime (771553) and next prime (771569).

It is not a de Polignac number, because 771561 - 2³ = 771553 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (771569) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2166 + ... + 2496.

2⁷⁷¹⁵⁶¹ is an apocalyptic number.

It is an amenable number.

771561 is a deficient number, since it is larger than the sum of its proper divisors (540503).

771561 is a wasteful number, since it uses less digits than its factorization.

771561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 381 (or 378 counting only the distinct ones).

The product of its digits is 1470, while the sum is 27.

The square root of 771561 is about 878.3854506992. The cubic root of 771561 is about 91.7184603534.

It can be divided in two parts, 7715 and 61, that added together give a 5-th power (7776 = 6⁵).

The spelling of 771561 in words is "seven hundred seventy-one thousand, five hundred sixty-one".