20991988403 has 2 divisors, whose sum is σ = 20991988404. Its totient is φ = 20991988402.

The previous prime is 20991988393. The next prime is 20991988429. The reversal of 20991988403 is 30488919902.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20991988403 - 2¹⁴ = 20991972019 is a prime.

It is a super-2 number, since 2×20991988403² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20991988103) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10495994201 + 10495994202.

It is an arithmetic number, because the mean of its divisors is an integer number (10495994202).

Almost surely, 2^20991988403 is an apocalyptic number.

20991988403 is a deficient number, since it is larger than the sum of its proper divisors (1).

20991988403 is an equidigital number, since it uses as much as digits as its factorization.

20991988403 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1119744, while the sum is 53.

The spelling of 20991988403 in words is "twenty billion, nine hundred ninety-one million, nine hundred eighty-eight thousand, four hundred three".