20148987721 has 2 divisors, whose sum is σ = 20148987722. Its totient is φ = 20148987720.

The previous prime is 20148987667. The next prime is 20148987797. The reversal of 20148987721 is 12778984102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12428905225 + 7720082496 = 111485^2 + 87864^2 .

It is a cyclic number.

It is not a de Polignac number, because 20148987721 - 2¹⁵ = 20148954953 is a prime.

It is not a weakly prime, because it can be changed into another prime (20148987821) 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, 10074493860 + 10074493861.

It is an arithmetic number, because the mean of its divisors is an integer number (10074493861).

Almost surely, 2^20148987721 is an apocalyptic number.

It is an amenable number.

20148987721 is a deficient number, since it is larger than the sum of its proper divisors (1).

20148987721 is an equidigital number, since it uses as much as digits as its factorization.

20148987721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 451584, while the sum is 49.

The spelling of 20148987721 in words is "twenty billion, one hundred forty-eight million, nine hundred eighty-seven thousand, seven hundred twenty-one".