21156463481 has 2 divisors, whose sum is σ = 21156463482. Its totient is φ = 21156463480.

The previous prime is 21156463477. The next prime is 21156463553. The reversal of 21156463481 is 18436465112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18627882256 + 2528581225 = 136484^2 + 50285^2 .

It is a cyclic number.

It is not a de Polignac number, because 21156463481 - 2² = 21156463477 is a prime.

It is a super-2 number, since 2×21156463481² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21156463441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10578231740 + 10578231741.

It is an arithmetic number, because the mean of its divisors is an integer number (10578231741).

Almost surely, 2^21156463481 is an apocalyptic number.

It is an amenable number.

21156463481 is a deficient number, since it is larger than the sum of its proper divisors (1).

21156463481 is an equidigital number, since it uses as much as digits as its factorization.

21156463481 is an evil number, because the sum of its binary digits is even.

The product of its digits is 138240, while the sum is 41.

The spelling of 21156463481 in words is "twenty-one billion, one hundred fifty-six million, four hundred sixty-three thousand, four hundred eighty-one".