21210520243 has 16 divisors (see below), whose sum is σ = 23712189696. Its totient is φ = 18810015840.

The previous prime is 21210520241. The next prime is 21210520273. The reversal of 21210520243 is 34202501212.

It is a happy number.

It is not a de Polignac number, because 21210520243 - 2¹ = 21210520241 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21210520241) 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, 63796 + ... + 215617.

It is an arithmetic number, because the mean of its divisors is an integer number (1482011856).

Almost surely, 2^21210520243 is an apocalyptic number.

21210520243 is a deficient number, since it is larger than the sum of its proper divisors (2501669453).

21210520243 is a wasteful number, since it uses less digits than its factorization.

21210520243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 279594.

The product of its (nonzero) digits is 960, while the sum is 22.

The spelling of 21210520243 in words is "twenty-one billion, two hundred ten million, five hundred twenty thousand, two hundred forty-three".