21494935381 has 2 divisors, whose sum is σ = 21494935382. Its totient is φ = 21494935380.

The previous prime is 21494935373. The next prime is 21494935421. The reversal of 21494935381 is 18353949412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11884270225 + 9610665156 = 109015^2 + 98034^2 .

It is a cyclic number.

It is not a de Polignac number, because 21494935381 - 2³ = 21494935373 is a prime.

It is a super-2 number, since 2×21494935381² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21494935081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10747467690 + 10747467691.

It is an arithmetic number, because the mean of its divisors is an integer number (10747467691).

Almost surely, 2^21494935381 is an apocalyptic number.

It is an amenable number.

21494935381 is a deficient number, since it is larger than the sum of its proper divisors (1).

21494935381 is an equidigital number, since it uses as much as digits as its factorization.

21494935381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 933120, while the sum is 49.

The spelling of 21494935381 in words is "twenty-one billion, four hundred ninety-four million, nine hundred thirty-five thousand, three hundred eighty-one".