775605721 has 16 divisors (see below), whose sum is σ = 853288128. Its totient is φ = 699148800.

The previous prime is 775605659. The next prime is 775605731. The reversal of 775605721 is 127506577.

It is a cyclic number.

It is not a de Polignac number, because 775605721 - 2¹⁵ = 775572953 is a prime.

It is not an unprimeable number, because it can be changed into a prime (775605731) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 813381 + ... + 814333.

It is an arithmetic number, because the mean of its divisors is an integer number (53330508).

Almost surely, 2^775605721 is an apocalyptic number.

It is an amenable number.

775605721 is a deficient number, since it is larger than the sum of its proper divisors (77682407).

775605721 is a wasteful number, since it uses less digits than its factorization.

775605721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1512.

The product of its (nonzero) digits is 102900, while the sum is 40.

The square root of 775605721 is about 27849.6987595916. The cubic root of 775605721 is about 918.7845168453.

The spelling of 775605721 in words is "seven hundred seventy-five million, six hundred five thousand, seven hundred twenty-one".