21013055 has 16 divisors (see below), whose sum is σ = 29044224. Its totient is φ = 14295840.

The previous prime is 21013049. The next prime is 21013061. The reversal of 21013055 is 55031012.

It is a Cunningham number, because it is equal to 4584²-1.

It is an interprime number because it is at equal distance from previous prime (21013049) and next prime (21013061).

It is not a de Polignac number, because 21013055 - 2⁶ = 21012991 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 2294 + ... + 6876.

It is an arithmetic number, because the mean of its divisors is an integer number (1815264).

Almost surely, 2^21013055 is an apocalyptic number.

21013055 is a deficient number, since it is larger than the sum of its proper divisors (8031169).

21013055 is a wasteful number, since it uses less digits than its factorization.

21013055 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4726.

The product of its (nonzero) digits is 150, while the sum is 17.

The square root of 21013055 is about 4583.9998909250. Note that the first 3 decimals coincide. The cubic root of 21013055 is about 275.9495768350.

Adding to 21013055 its reverse (55031012), we get a palindrome (76044067).

The spelling of 21013055 in words is "twenty-one million, thirteen thousand, fifty-five".