21125570081 has 64 divisors (see below), whose sum is σ = 29579821056. Its totient is φ = 14575334400.

The previous prime is 21125570069. The next prime is 21125570101. The reversal of 21125570081 is 18007552112.

It is not a de Polignac number, because 21125570081 - 2¹⁰ = 21125569057 is a prime.

It is a super-2 number, since 2×21125570081² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21125570051) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1830776 + ... + 1842278.

It is an arithmetic number, because the mean of its divisors is an integer number (462184704).

Almost surely, 2^21125570081 is an apocalyptic number.

It is an amenable number.

21125570081 is a deficient number, since it is larger than the sum of its proper divisors (8454250975).

21125570081 is a wasteful number, since it uses less digits than its factorization.

21125570081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11622.

The product of its (nonzero) digits is 5600, while the sum is 32.

The spelling of 21125570081 in words is "twenty-one billion, one hundred twenty-five million, five hundred seventy thousand, eighty-one".