21155235524 has 6 divisors (see below), whose sum is σ = 37021662174. Its totient is φ = 10577617760.

The previous prime is 21155235469. The next prime is 21155235529. The reversal of 21155235524 is 42553255112.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 19984911424 + 1170324100 = 141368^2 + 34210^2 .

It is not an unprimeable number, because it can be changed into a prime (21155235529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2644404437 + ... + 2644404444.

It is an arithmetic number, because the mean of its divisors is an integer number (6170277029).

Almost surely, 2^21155235524 is an apocalyptic number.

It is an amenable number.

21155235524 is a deficient number, since it is larger than the sum of its proper divisors (15866426650).

21155235524 is a wasteful number, since it uses less digits than its factorization.

21155235524 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5288808885 (or 5288808883 counting only the distinct ones).

The product of its digits is 60000, while the sum is 35.

The spelling of 21155235524 in words is "twenty-one billion, one hundred fifty-five million, two hundred thirty-five thousand, five hundred twenty-four".