21122155 has 8 divisors (see below), whose sum is σ = 25467984. Its totient is φ = 16816800.

The previous prime is 21122111. The next prime is 21122161. The reversal of 21122155 is 55122112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21122155 - 2¹⁷ = 20991083 is a prime.

It is a super-2 number, since 2×21122155² = 892290863688050, which contains 22 as substring.

It is a Duffinian 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 7 ways as a sum of consecutive naturals, for example, 8956 + ... + 11065.

It is an arithmetic number, because the mean of its divisors is an integer number (3183498).

Almost surely, 2^21122155 is an apocalyptic number.

21122155 is a deficient number, since it is larger than the sum of its proper divisors (4345829).

21122155 is a wasteful number, since it uses less digits than its factorization.

21122155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20237.

The product of its digits is 200, while the sum is 19.

The square root of 21122155 is about 4595.8845720927. The cubic root of 21122155 is about 276.4263303719.

Adding to 21122155 its reverse (55122112), we get a palindrome (76244267).

It can be divided in two parts, 211 and 22155, that added together give a triangular number (22366 = T₂₁₁).

The spelling of 21122155 in words is "twenty-one million, one hundred twenty-two thousand, one hundred fifty-five".