21335017481 has 2 divisors, whose sum is σ = 21335017482. Its totient is φ = 21335017480.

The previous prime is 21335017477. The next prime is 21335017523. The reversal of 21335017481 is 18471053312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18430777600 + 2904239881 = 135760^2 + 53891^2 .

It is a cyclic number.

It is not a de Polignac number, because 21335017481 - 2² = 21335017477 is a prime.

It is a super-2 number, since 2×21335017481² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21335017381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10667508740 + 10667508741.

It is an arithmetic number, because the mean of its divisors is an integer number (10667508741).

Almost surely, 2^21335017481 is an apocalyptic number.

It is an amenable number.

21335017481 is a deficient number, since it is larger than the sum of its proper divisors (1).

21335017481 is an equidigital number, since it uses as much as digits as its factorization.

21335017481 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20160, while the sum is 35.

The spelling of 21335017481 in words is "twenty-one billion, three hundred thirty-five million, seventeen thousand, four hundred eighty-one".