5121655621 has 4 divisors (see below), whose sum is σ = 5138019052. Its totient is φ = 5105292192.

The previous prime is 5121655559. The next prime is 5121655639. The reversal of 5121655621 is 1265561215.

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 1392110721 + 3729544900 = 37311^2 + 61070^2 .

It is a cyclic number.

It is not a de Polignac number, because 5121655621 - 2¹¹ = 5121653573 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (5121658621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8181246 + ... + 8181871.

It is an arithmetic number, because the mean of its divisors is an integer number (1284504763).

Almost surely, 2^5121655621 is an apocalyptic number.

It is an amenable number.

5121655621 is a deficient number, since it is larger than the sum of its proper divisors (16363431).

5121655621 is a wasteful number, since it uses less digits than its factorization.

5121655621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16363430.

The product of its digits is 18000, while the sum is 34.

The square root of 5121655621 is about 71565.7433483367. The cubic root of 5121655621 is about 1723.7335094689.

The spelling of 5121655621 in words is "five billion, one hundred twenty-one million, six hundred fifty-five thousand, six hundred twenty-one".