21213156340 has 24 divisors (see below), whose sum is σ = 44563180032. Its totient is φ = 8482300320.

The previous prime is 21213156323. The next prime is 21213156383. The reversal of 21213156340 is 4365131212.

It is a junction number, because it is equal to n+sod(n) for n = 21213156299 and 21213156308.

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, 125956 + ... + 241435.

It is an arithmetic number, because the mean of its divisors is an integer number (1856799168).

Almost surely, 2^21213156340 is an apocalyptic number.

21213156340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21213156340 is an abundant number, since it is smaller than the sum of its proper divisors (23350023692).

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

21213156340 is a wasteful number, since it uses less digits than its factorization.

21213156340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 370287 (or 370285 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 28.

Adding to 21213156340 its reverse (4365131212), we get a palindrome (25578287552).

The spelling of 21213156340 in words is "twenty-one billion, two hundred thirteen million, one hundred fifty-six thousand, three hundred forty".