21111025521 has 16 divisors (see below), whose sum is σ = 28275406848. Its totient is φ = 14010450000.

The previous prime is 21111025519. The next prime is 21111025547. The reversal of 21111025521 is 12552011112.

It is not a de Polignac number, because 21111025521 - 2¹ = 21111025519 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21111025591) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 719896 + ... + 748646.

It is an arithmetic number, because the mean of its divisors is an integer number (1767212928).

Almost surely, 2^21111025521 is an apocalyptic number.

It is an amenable number.

21111025521 is a deficient number, since it is larger than the sum of its proper divisors (7164381327).

21111025521 is a wasteful number, since it uses less digits than its factorization.

21111025521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29852.

The product of its (nonzero) digits is 200, while the sum is 21.

Adding to 21111025521 its reverse (12552011112), we get a palindrome (33663036633).

The spelling of 21111025521 in words is "twenty-one billion, one hundred eleven million, twenty-five thousand, five hundred twenty-one".