21080126581 has 4 divisors (see below), whose sum is σ = 21099958432. Its totient is φ = 21060294732.

The previous prime is 21080126567. The next prime is 21080126657. The reversal of 21080126581 is 18562108012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21080126581 - 2¹⁵ = 21080093813 is a prime.

It is a super-2 number, since 2×21080126581² (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 (21080126381) 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, 9914331 + ... + 9916456.

It is an arithmetic number, because the mean of its divisors is an integer number (5274989608).

Almost surely, 2^21080126581 is an apocalyptic number.

It is an amenable number.

21080126581 is a deficient number, since it is larger than the sum of its proper divisors (19831851).

21080126581 is a wasteful number, since it uses less digits than its factorization.

21080126581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19831850.

The product of its (nonzero) digits is 7680, while the sum is 34.

The spelling of 21080126581 in words is "twenty-one billion, eighty million, one hundred twenty-six thousand, five hundred eighty-one".