7720836421 has 4 divisors (see below), whose sum is σ = 7753973292. Its totient is φ = 7687699552.

The previous prime is 7720836413. The next prime is 7720836437. The reversal of 7720836421 is 1246380277.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3239203396 + 4481633025 = 56914^2 + 66945^2 .

It is a cyclic number.

It is not a de Polignac number, because 7720836421 - 2³ = 7720836413 is a prime.

It is a super-2 number, since 2×7720836421² (a number of 21 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7720836521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16568086 + ... + 16568551.

It is an arithmetic number, because the mean of its divisors is an integer number (1938493323).

Almost surely, 2^7720836421 is an apocalyptic number.

It is an amenable number.

7720836421 is a deficient number, since it is larger than the sum of its proper divisors (33136871).

7720836421 is a wasteful number, since it uses less digits than its factorization.

7720836421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33136870.

The product of its (nonzero) digits is 112896, while the sum is 40.

The square root of 7720836421 is about 87868.2901904891. The cubic root of 7720836421 is about 1976.4603989747.

The spelling of 7720836421 in words is "seven billion, seven hundred twenty million, eight hundred thirty-six thousand, four hundred twenty-one".