21210099973 has 2 divisors, whose sum is σ = 21210099974. Its totient is φ = 21210099972.

The previous prime is 21210099971. The next prime is 21210099979. The reversal of 21210099973 is 37999001212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19860419329 + 1349680644 = 140927^2 + 36738^2 .

It is a cyclic number.

It is not a de Polignac number, because 21210099973 - 2¹ = 21210099971 is a prime.

Together with 21210099971, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21210099971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605049986 + 10605049987.

It is an arithmetic number, because the mean of its divisors is an integer number (10605049987).

Almost surely, 2^21210099973 is an apocalyptic number.

It is an amenable number.

21210099973 is a deficient number, since it is larger than the sum of its proper divisors (1).

21210099973 is an equidigital number, since it uses as much as digits as its factorization.

21210099973 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 61236, while the sum is 43.

The spelling of 21210099973 in words is "twenty-one billion, two hundred ten million, ninety-nine thousand, nine hundred seventy-three".