21312102440 has 32 divisors (see below), whose sum is σ = 47956401000. Its totient is φ = 8524099584.

The previous prime is 21312102439. The next prime is 21312102463. The reversal of 21312102440 is 4420121312.

It can be written as a sum of positive squares in 4 ways, for example, as 19577046724 + 1735055716 = 139918^2 + 41654^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

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, 834176 + ... + 859344.

Almost surely, 2^21312102440 is an apocalyptic number.

21312102440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21312102440 is an abundant number, since it is smaller than the sum of its proper divisors (26644298560).

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

21312102440 is a wasteful number, since it uses less digits than its factorization.

21312102440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46349 (or 46345 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 20.

Adding to 21312102440 its reverse (4420121312), we get a palindrome (25732223752).

The spelling of 21312102440 in words is "twenty-one billion, three hundred twelve million, one hundred two thousand, four hundred forty".