18821827621 has 2 divisors, whose sum is σ = 18821827622. Its totient is φ = 18821827620.

The previous prime is 18821827547. The next prime is 18821827643. The reversal of 18821827621 is 12672812881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11381902596 + 7439925025 = 106686^2 + 86255^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18821827621 is a prime.

It is a super-2 number, since 2×18821827621² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18821827681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9410913810 + 9410913811.

It is an arithmetic number, because the mean of its divisors is an integer number (9410913811).

Almost surely, 2^18821827621 is an apocalyptic number.

It is an amenable number.

18821827621 is a deficient number, since it is larger than the sum of its proper divisors (1).

18821827621 is an equidigital number, since it uses as much as digits as its factorization.

18821827621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 172032, while the sum is 46.

The spelling of 18821827621 in words is "eighteen billion, eight hundred twenty-one million, eight hundred twenty-seven thousand, six hundred twenty-one".