21131957481 has 8 divisors (see below), whose sum is σ = 29147527680. Its totient is φ = 13602179472.

The previous prime is 21131957461. The next prime is 21131957521. The reversal of 21131957481 is 18475913112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21131957481 - 2⁶ = 21131957417 is a prime.

It is a super-2 number, since 2×21131957481² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21131957461) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 121447945 + ... + 121448118.

It is an arithmetic number, because the mean of its divisors is an integer number (3643440960).

Almost surely, 2^21131957481 is an apocalyptic number.

It is an amenable number.

21131957481 is a deficient number, since it is larger than the sum of its proper divisors (8015570199).

21131957481 is a wasteful number, since it uses less digits than its factorization.

21131957481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 242896095.

The product of its digits is 60480, while the sum is 42.

The spelling of 21131957481 in words is "twenty-one billion, one hundred thirty-one million, nine hundred fifty-seven thousand, four hundred eighty-one".