21234343440 has 40 divisors (see below), whose sum is σ = 65826465408. Its totient is φ = 5662491520.

The previous prime is 21234343439. The next prime is 21234343447. The reversal of 21234343440 is 4434343212.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 21234343398 and 21234343407.

It is not an unprimeable number, because it can be changed into a prime (21234343447) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44237976 + ... + 44238455.

Almost surely, 2^21234343440 is an apocalyptic number.

21234343440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21234343440 is an abundant number, since it is smaller than the sum of its proper divisors (44592121968).

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

21234343440 is a wasteful number, since it uses less digits than its factorization.

21234343440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88476447 (or 88476441 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 30.

Adding to 21234343440 its reverse (4434343212), we get a palindrome (25668686652).

The spelling of 21234343440 in words is "twenty-one billion, two hundred thirty-four million, three hundred forty-three thousand, four hundred forty".