21415081 has 2 divisors, whose sum is σ = 21415082. Its totient is φ = 21415080.

The previous prime is 21415067. The next prime is 21415099. The reversal of 21415081 is 18051412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15210000 + 6205081 = 3900^2 + 2491^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21415081 is a prime.

It is a super-2 number, since 2×21415081² = 917211388473122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21415181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10707540 + 10707541.

It is an arithmetic number, because the mean of its divisors is an integer number (10707541).

Almost surely, 2^21415081 is an apocalyptic number.

It is an amenable number.

21415081 is a deficient number, since it is larger than the sum of its proper divisors (1).

21415081 is an equidigital number, since it uses as much as digits as its factorization.

21415081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 320, while the sum is 22.

The square root of 21415081 is about 4627.6431366301. The cubic root of 21415081 is about 277.6983123743.

Adding to 21415081 its reverse (18051412), we get a palindrome (39466493).

The spelling of 21415081 in words is "twenty-one million, four hundred fifteen thousand, eighty-one".