21019250128 has 10 divisors (see below), whose sum is σ = 40724797154. Its totient is φ = 10509625056.

The previous prime is 21019250123. The next prime is 21019250129. The reversal of 21019250128 is 82105291012.

It can be written as a sum of positive squares in only one way, i.e., 20399837584 + 619412544 = 142828^2 + 24888^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21019250128.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21019250123) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 656851551 + ... + 656851582.

Almost surely, 2^21019250128 is an apocalyptic number.

It is an amenable number.

21019250128 is a deficient number, since it is larger than the sum of its proper divisors (19705547026).

21019250128 is a wasteful number, since it uses less digits than its factorization.

21019250128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1313703141 (or 1313703135 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 31.

The spelling of 21019250128 in words is "twenty-one billion, nineteen million, two hundred fifty thousand, one hundred twenty-eight".