21213236340 has 48 divisors (see below), whose sum is σ = 65996736960. Its totient is φ = 5656862880.

The previous prime is 21213236321. The next prime is 21213236351. The reversal of 21213236340 is 4363231212.

21213236340 is a `hidden beast` number, since 2 + 1 + 2 + 1 + 3 + 23 + 634 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19641346 + ... + 19642425.

It is an arithmetic number, because the mean of its divisors is an integer number (1374932020).

Almost surely, 2^21213236340 is an apocalyptic number.

21213236340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21213236340 is an abundant number, since it is smaller than the sum of its proper divisors (44783500620).

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

21213236340 is a wasteful number, since it uses less digits than its factorization.

21213236340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39283789 (or 39283781 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 27.

Adding to 21213236340 its reverse (4363231212), we get a palindrome (25576467552).

The spelling of 21213236340 in words is "twenty-one billion, two hundred thirteen million, two hundred thirty-six thousand, three hundred forty".