21420201240240 has 80 divisors (see below), whose sum is σ = 72439226021376. Its totient is φ = 5192776057600.

The previous prime is 21420201240239. The next prime is 21420201240247. The reversal of 21420201240240 is 4204210202412.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21420201240240.

It is not an unprimeable number, because it can be changed into a prime (21420201240247) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4056853656 + ... + 4056858935.

Almost surely, 2^{21420201240240} is an apocalyptic number.

21420201240240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21420201240240 is an abundant number, since it is smaller than the sum of its proper divisors (51019024781136).

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

21420201240240 is a wasteful number, since it uses less digits than its factorization.

21420201240240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8113712618 (or 8113712612 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 24.

Adding to 21420201240240 its reverse (4204210202412), we get a palindrome (25624411442652).

The spelling of 21420201240240 in words is "twenty-one trillion, four hundred twenty billion, two hundred one million, two hundred forty thousand, two hundred forty".