21471155 has 16 divisors (see below), whose sum is σ = 26438400. Its totient is φ = 16734432.

The previous prime is 21471139. The next prime is 21471157. The reversal of 21471155 is 55117412.

It is a cyclic number.

It is not a de Polignac number, because 21471155 - 2⁴ = 21471139 is a prime.

It is a super-3 number, since 3×21471155³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (21471157) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 35546 + ... + 36144.

It is an arithmetic number, because the mean of its divisors is an integer number (1652400).

Almost surely, 2^21471155 is an apocalyptic number.

21471155 is a deficient number, since it is larger than the sum of its proper divisors (4967245).

21471155 is a wasteful number, since it uses less digits than its factorization.

21471155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 778.

The product of its digits is 1400, while the sum is 26.

The square root of 21471155 is about 4633.6977674423. The cubic root of 21471155 is about 277.9404794680.

Adding to 21471155 its reverse (55117412), we get a palindrome (76588567).

The spelling of 21471155 in words is "twenty-one million, four hundred seventy-one thousand, one hundred fifty-five".