21008215028 has 6 divisors (see below), whose sum is σ = 36764376306. Its totient is φ = 10504107512.

The previous prime is 21008215027. The next prime is 21008215057. The reversal of 21008215028 is 82051280012.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 18069274084 + 2938940944 = 134422^2 + 54212^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21008215027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2626026875 + ... + 2626026882.

It is an arithmetic number, because the mean of its divisors is an integer number (6127396051).

Almost surely, 2^21008215028 is an apocalyptic number.

It is an amenable number.

21008215028 is a deficient number, since it is larger than the sum of its proper divisors (15756161278).

21008215028 is a wasteful number, since it uses less digits than its factorization.

21008215028 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5252053761 (or 5252053759 counting only the distinct ones).

The product of its (nonzero) digits is 2560, while the sum is 29.

It can be divided in two parts, 2100 and 8215028, that added together give a palindrome (8217128).

The spelling of 21008215028 in words is "twenty-one billion, eight million, two hundred fifteen thousand, twenty-eight".