21030400073 has 2 divisors, whose sum is σ = 21030400074. Its totient is φ = 21030400072.

The previous prime is 21030400063. The next prime is 21030400109. The reversal of 21030400073 is 37000403012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21000936889 + 29463184 = 144917^2 + 5428^2 .

It is a cyclic number.

It is not a de Polignac number, because 21030400073 - 2¹² = 21030395977 is a prime.

It is not a weakly prime, because it can be changed into another prime (21030400043) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10515200036 + 10515200037.

It is an arithmetic number, because the mean of its divisors is an integer number (10515200037).

Almost surely, 2^21030400073 is an apocalyptic number.

It is an amenable number.

21030400073 is a deficient number, since it is larger than the sum of its proper divisors (1).

21030400073 is an equidigital number, since it uses as much as digits as its factorization.

21030400073 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 504, while the sum is 20.

Adding to 21030400073 its reverse (37000403012), we get a palindrome (58030803085).

The spelling of 21030400073 in words is "twenty-one billion, thirty million, four hundred thousand, seventy-three".