21021043155 has 32 divisors (see below), whose sum is σ = 38457076224. Its totient is φ = 9604970496.

The previous prime is 21021043151. The next prime is 21021043157. The reversal of 21021043155 is 55134012012.

It is a happy number.

It is not a de Polignac number, because 21021043155 - 2² = 21021043151 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21021043151) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 174492 + ... + 269238.

It is an arithmetic number, because the mean of its divisors is an integer number (1201783632).

Almost surely, 2^21021043155 is an apocalyptic number.

21021043155 is a deficient number, since it is larger than the sum of its proper divisors (17436033069).

21021043155 is a wasteful number, since it uses less digits than its factorization.

21021043155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96875.

The product of its (nonzero) digits is 1200, while the sum is 24.

Adding to 21021043155 its reverse (55134012012), we get a palindrome (76155055167).

The spelling of 21021043155 in words is "twenty-one billion, twenty-one million, forty-three thousand, one hundred fifty-five".