21502443240154 has 12 divisors (see below), whose sum is σ = 34262543641374. Its totient is φ = 10118796818624.

The previous prime is 21502443240139. The next prime is 21502443240199. The reversal of 21502443240154 is 45104234420512.

It can be written as a sum of positive squares in 3 ways, for example, as 17296158088225 + 4206285151929 = 4158865^2 + 2050923^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 18600728869 + ... + 18600730024.

Almost surely, 2^{21502443240154} is an apocalyptic number.

21502443240154 is a deficient number, since it is larger than the sum of its proper divisors (12760100401220).

21502443240154 is a wasteful number, since it uses less digits than its factorization.

21502443240154 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37201458929 (or 37201458912 counting only the distinct ones).

The product of its (nonzero) digits is 153600, while the sum is 37.

Adding to 21502443240154 its reverse (45104234420512), we get a palindrome (66606677660666).

The spelling of 21502443240154 in words is "twenty-one trillion, five hundred two billion, four hundred forty-three million, two hundred forty thousand, one hundred fifty-four".