21517073 has 2 divisors, whose sum is σ = 21517074. Its totient is φ = 21517072.

The previous prime is 21517057. The next prime is 21517109. The reversal of 21517073 is 37071512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12475024 + 9042049 = 3532^2 + 3007^2 .

It is a cyclic number.

It is not a de Polignac number, because 21517073 - 2⁴ = 21517057 is a prime.

It is not a weakly prime, because it can be changed into another prime (21517373) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10758536 + 10758537.

It is an arithmetic number, because the mean of its divisors is an integer number (10758537).

Almost surely, 2^21517073 is an apocalyptic number.

It is an amenable number.

21517073 is a deficient number, since it is larger than the sum of its proper divisors (1).

21517073 is an equidigital number, since it uses as much as digits as its factorization.

21517073 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1470, while the sum is 26.

The square root of 21517073 is about 4638.6499113427. The cubic root of 21517073 is about 278.1384719814.

Adding to 21517073 its reverse (37071512), we get a palindrome (58588585).

It can be divided in two parts, 215 and 17073, that multiplied together give a triangular number (3670695 = T₂₇₀₉).

The spelling of 21517073 in words is "twenty-one million, five hundred seventeen thousand, seventy-three".