21050551121 has 4 divisors (see below), whose sum is σ = 22288818852. Its totient is φ = 19812283392.

The previous prime is 21050551099. The next prime is 21050551169. The reversal of 21050551121 is 12115505012.

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 6904779025 + 14145772096 = 83095^2 + 118936^2 .

It is a cyclic number.

It is not a de Polignac number, because 21050551121 - 2¹⁴ = 21050534737 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21050551721) 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, 619133840 + ... + 619133873.

It is an arithmetic number, because the mean of its divisors is an integer number (5572204713).

Almost surely, 2^21050551121 is an apocalyptic number.

It is an amenable number.

21050551121 is a deficient number, since it is larger than the sum of its proper divisors (1238267731).

21050551121 is a wasteful number, since it uses less digits than its factorization.

21050551121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1238267730.

The product of its (nonzero) digits is 500, while the sum is 23.

The spelling of 21050551121 in words is "twenty-one billion, fifty million, five hundred fifty-one thousand, one hundred twenty-one".