21010073 has 6 divisors (see below), whose sum is σ = 24440346. Its totient is φ = 18008592.

The previous prime is 21010069. The next prime is 21010097. The reversal of 21010073 is 37001012.

It can be written as a sum of positive squares in only one way, i.e., 12201049 + 8809024 = 3493^2 + 2968^2 .

It is not a de Polignac number, because 21010073 - 2² = 21010069 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21010013) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 214340 + ... + 214437.

It is an arithmetic number, because the mean of its divisors is an integer number (4073391).

Almost surely, 2^21010073 is an apocalyptic number.

It is an amenable number.

21010073 is a deficient number, since it is larger than the sum of its proper divisors (3430273).

21010073 is an equidigital number, since it uses as much as digits as its factorization.

21010073 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 428791 (or 428784 counting only the distinct ones).

The product of its (nonzero) digits is 42, while the sum is 14.

The square root of 21010073 is about 4583.6746175967. The cubic root of 21010073 is about 275.9365227191.

Adding to 21010073 its reverse (37001012), we get a palindrome (58011085).

The spelling of 21010073 in words is "twenty-one million, ten thousand, seventy-three".