21521112405 has 32 divisors (see below), whose sum is σ = 37097284224. Its totient is φ = 10590794496.

The previous prime is 21521112359. The next prime is 21521112427. The reversal of 21521112405 is 50421112512.

It is a happy number.

It is not a de Polignac number, because 21521112405 - 2²⁴ = 21504335189 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 501402 + ... + 542628.

It is an arithmetic number, because the mean of its divisors is an integer number (1159290132).

Almost surely, 2^21521112405 is an apocalyptic number.

It is an amenable number.

21521112405 is a deficient number, since it is larger than the sum of its proper divisors (15576171819).

21521112405 is a wasteful number, since it uses less digits than its factorization.

21521112405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43925.

The product of its (nonzero) digits is 800, while the sum is 24.

Adding to 21521112405 its reverse (50421112512), we get a palindrome (71942224917).

The spelling of 21521112405 in words is "twenty-one billion, five hundred twenty-one million, one hundred twelve thousand, four hundred five".