21034021755 has 64 divisors (see below), whose sum is σ = 37015004160. Its totient is φ = 10164650496.

The previous prime is 21034021753. The next prime is 21034021781. The reversal of 21034021755 is 55712043012.

It is not a de Polignac number, because 21034021755 - 2¹ = 21034021753 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21034021751) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 510432 + ... + 550098.

It is an arithmetic number, because the mean of its divisors is an integer number (578359440).

Almost surely, 2^21034021755 is an apocalyptic number.

21034021755 is a deficient number, since it is larger than the sum of its proper divisors (15980982405).

21034021755 is a wasteful number, since it uses less digits than its factorization.

21034021755 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39780.

The product of its (nonzero) digits is 8400, while the sum is 30.

Adding to 21034021755 its reverse (55712043012), we get a palindrome (76746064767).

The spelling of 21034021755 in words is "twenty-one billion, thirty-four million, twenty-one thousand, seven hundred fifty-five".