21004155552 has 48 divisors (see below), whose sum is σ = 55149075072. Its totient is φ = 6999713280.

The previous prime is 21004155547. The next prime is 21004155677. The reversal of 21004155552 is 25555140012.

It is a tau number, because it is divible by the number of its divisors (48).

It is a super-2 number, since 2×21004155552² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 416908 + ... + 464564.

It is an arithmetic number, because the mean of its divisors is an integer number (1148939064).

Almost surely, 2^21004155552 is an apocalyptic number.

It is an amenable number.

21004155552 is an abundant number, since it is smaller than the sum of its proper divisors (34144919520).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21004155552 is a wasteful number, since it uses less digits than its factorization.

21004155552 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52261 (or 52253 counting only the distinct ones).

The product of its (nonzero) digits is 10000, while the sum is 30.

Adding to 21004155552 its reverse (25555140012), we get a palindrome (46559295564).

The spelling of 21004155552 in words is "twenty-one billion, four million, one hundred fifty-five thousand, five hundred fifty-two".