21401155 has 8 divisors (see below), whose sum is σ = 26798112. Its totient is φ = 16376448.

The previous prime is 21401137. The next prime is 21401203. The reversal of 21401155 is 55110412.

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

It is a cyclic number.

It is not a de Polignac number, because 21401155 - 2⁵ = 21401123 is a prime.

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, 92934 + ... + 93163.

It is an arithmetic number, because the mean of its divisors is an integer number (3349764).

Almost surely, 2^21401155 is an apocalyptic number.

21401155 is a deficient number, since it is larger than the sum of its proper divisors (5396957).

21401155 is a wasteful number, since it uses less digits than its factorization.

21401155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186125.

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

The square root of 21401155 is about 4626.1382383150. The cubic root of 21401155 is about 277.6381045660.

Adding to 21401155 its reverse (55110412), we get a palindrome (76511567).

The spelling of 21401155 in words is "twenty-one million, four hundred one thousand, one hundred fifty-five".