21311212340 has 48 divisors (see below), whose sum is σ = 49325419584. Its totient is φ = 7669632000.

The previous prime is 21311212337. The next prime is 21311212361. The reversal of 21311212340 is 4321211312.

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

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, 477986 + ... + 520665.

It is an arithmetic number, because the mean of its divisors is an integer number (1027612908).

Almost surely, 2^21311212340 is an apocalyptic number.

21311212340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21311212340 is an abundant number, since it is smaller than the sum of its proper divisors (28014207244).

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

21311212340 is a wasteful number, since it uses less digits than its factorization.

21311212340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 998768 (or 998766 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 20.

Adding to 21311212340 its reverse (4321211312), we get a palindrome (25632423652).

The spelling of 21311212340 in words is "twenty-one billion, three hundred eleven million, two hundred twelve thousand, three hundred forty".