21333555409 has 2 divisors, whose sum is σ = 21333555410. Its totient is φ = 21333555408.

The previous prime is 21333555371. The next prime is 21333555449. The reversal of 21333555409 is 90455533312.

It is an a-pointer prime, because the next prime (21333555449) can be obtained adding 21333555409 to its sum of digits (40).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17308033600 + 4025521809 = 131560^2 + 63447^2 .

It is a cyclic number.

It is not a de Polignac number, because 21333555409 - 2⁹ = 21333554897 is a prime.

It is not a weakly prime, because it can be changed into another prime (21333555449) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10666777704 + 10666777705.

It is an arithmetic number, because the mean of its divisors is an integer number (10666777705).

Almost surely, 2^21333555409 is an apocalyptic number.

It is an amenable number.

21333555409 is a deficient number, since it is larger than the sum of its proper divisors (1).

21333555409 is an equidigital number, since it uses as much as digits as its factorization.

21333555409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 243000, while the sum is 40.

The spelling of 21333555409 in words is "twenty-one billion, three hundred thirty-three million, five hundred fifty-five thousand, four hundred nine".