20424211721 has 2 divisors, whose sum is σ = 20424211722. Its totient is φ = 20424211720.

The previous prime is 20424211711. The next prime is 20424211729. The reversal of 20424211721 is 12711242402.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18748455625 + 1675756096 = 136925^2 + 40936^2 .

It is a cyclic number.

It is not a de Polignac number, because 20424211721 - 2⁶ = 20424211657 is a prime.

It is not a weakly prime, because it can be changed into another prime (20424211729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10212105860 + 10212105861.

It is an arithmetic number, because the mean of its divisors is an integer number (10212105861).

Almost surely, 2^20424211721 is an apocalyptic number.

It is an amenable number.

20424211721 is a deficient number, since it is larger than the sum of its proper divisors (1).

20424211721 is an equidigital number, since it uses as much as digits as its factorization.

20424211721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1792, while the sum is 26.

The spelling of 20424211721 in words is "twenty billion, four hundred twenty-four million, two hundred eleven thousand, seven hundred twenty-one".