21095134981 has 4 divisors (see below), whose sum is σ = 22336025292. Its totient is φ = 19854244672.

The previous prime is 21095134961. The next prime is 21095135011. The reversal of 21095134981 is 18943159012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8346466881 + 12748668100 = 91359^2 + 112910^2 .

It is a cyclic number.

It is not a de Polignac number, because 21095134981 - 2⁹ = 21095134469 is a prime.

It is a super-2 number, since 2×21095134981² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21095134901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 620445130 + ... + 620445163.

It is an arithmetic number, because the mean of its divisors is an integer number (5584006323).

Almost surely, 2^21095134981 is an apocalyptic number.

It is an amenable number.

21095134981 is a deficient number, since it is larger than the sum of its proper divisors (1240890311).

21095134981 is a wasteful number, since it uses less digits than its factorization.

21095134981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1240890310.

The product of its (nonzero) digits is 77760, while the sum is 43.

The spelling of 21095134981 in words is "twenty-one billion, ninety-five million, one hundred thirty-four thousand, nine hundred eighty-one".