21224512525561 has 4 divisors (see below), whose sum is σ = 21366958918500. Its totient is φ = 21082066132624.

The previous prime is 21224512525483. The next prime is 21224512525793. The reversal of 21224512525561 is 16552521542212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2318051925225 + 18906460600336 = 1522515^2 + 4348156^2 .

It is a cyclic number.

It is not a de Polignac number, because 21224512525561 - 2²⁷ = 21224378307833 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21224512522561) 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, 71223196246 + ... + 71223196543.

It is an arithmetic number, because the mean of its divisors is an integer number (5341739729625).

Almost surely, 2^{21224512525561} is an apocalyptic number.

It is an amenable number.

21224512525561 is a deficient number, since it is larger than the sum of its proper divisors (142446392939).

21224512525561 is a wasteful number, since it uses less digits than its factorization.

21224512525561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142446392938.

The product of its digits is 480000, while the sum is 43.

The spelling of 21224512525561 in words is "twenty-one trillion, two hundred twenty-four billion, five hundred twelve million, five hundred twenty-five thousand, five hundred sixty-one".