21218217340 has 24 divisors (see below), whose sum is σ = 44586051552. Its totient is φ = 8481992640.

The previous prime is 21218217331. The next prime is 21218217353. The reversal of 21218217340 is 4371281212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 297951 + ... + 362230.

It is an arithmetic number, because the mean of its divisors is an integer number (1857752148).

Almost surely, 2^21218217340 is an apocalyptic number.

21218217340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21218217340 is an abundant number, since it is smaller than the sum of its proper divisors (23367834212).

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

21218217340 is a wasteful number, since it uses less digits than its factorization.

21218217340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 661797 (or 661795 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 31.

Adding to 21218217340 its reverse (4371281212), we get a palindrome (25589498552).

The spelling of 21218217340 in words is "twenty-one billion, two hundred eighteen million, two hundred seventeen thousand, three hundred forty".