7761720821 has 16 divisors (see below), whose sum is σ = 8567451648. Its totient is φ = 6999456000.

The previous prime is 7761720817. The next prime is 7761720853. The reversal of 7761720821 is 1280271677.

It is a cyclic number.

It is not a de Polignac number, because 7761720821 - 2² = 7761720817 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7761722821) 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, 19685 + ... + 126138.

It is an arithmetic number, because the mean of its divisors is an integer number (535465728).

Almost surely, 2^7761720821 is an apocalyptic number.

It is an amenable number.

7761720821 is a deficient number, since it is larger than the sum of its proper divisors (805730827).

7761720821 is a wasteful number, since it uses less digits than its factorization.

7761720821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145972.

The product of its (nonzero) digits is 65856, while the sum is 41.

The square root of 7761720821 is about 88100.6289478117. The cubic root of 7761720821 is about 1979.9429311341.

The spelling of 7761720821 in words is "seven billion, seven hundred sixty-one million, seven hundred twenty thousand, eight hundred twenty-one".