21011518 has 16 divisors (see below), whose sum is σ = 34634880. Its totient is φ = 9480600.

The previous prime is 21011513. The next prime is 21011519. The reversal of 21011518 is 81511012.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21011495 and 21011504.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011513) 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 in 7 ways as a sum of consecutive naturals, for example, 378 + ... + 6493.

It is an arithmetic number, because the mean of its divisors is an integer number (2164680).

Almost surely, 2^21011518 is an apocalyptic number.

21011518 is a deficient number, since it is larger than the sum of its proper divisors (13623362).

21011518 is a wasteful number, since it uses less digits than its factorization.

21011518 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7023.

The product of its (nonzero) digits is 80, while the sum is 19.

The square root of 21011518 is about 4583.8322395131. The cubic root of 21011518 is about 275.9428485599.

The spelling of 21011518 in words is "twenty-one million, eleven thousand, five hundred eighteen".