21030655 has 16 divisors (see below), whose sum is σ = 26722080. Its totient is φ = 15861888.

The previous prime is 21030637. The next prime is 21030677. The reversal of 21030655 is 55603012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21030655 - 2¹⁷ = 20899583 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4549 + ... + 7921.

It is an arithmetic number, because the mean of its divisors is an integer number (1670130).

Almost surely, 2^21030655 is an apocalyptic number.

21030655 is a deficient number, since it is larger than the sum of its proper divisors (5691425).

21030655 is a wasteful number, since it uses less digits than its factorization.

21030655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3450.

The product of its (nonzero) digits is 900, while the sum is 22.

The square root of 21030655 is about 4585.9192099295. The cubic root of 21030655 is about 276.0265981158.

Adding to 21030655 its reverse (55603012), we get a palindrome (76633667).

The spelling of 21030655 in words is "twenty-one million, thirty thousand, six hundred fifty-five".