21340243720 has 16 divisors (see below), whose sum is σ = 48015548460. Its totient is φ = 8536097472.

The previous prime is 21340243697. The next prime is 21340243741. The reversal of 21340243720 is 2734204312.

It can be written as a sum of positive squares in 2 ways, for example, as 19342690084 + 1997553636 = 139078^2 + 44694^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 266753007 + ... + 266753086.

Almost surely, 2^21340243720 is an apocalyptic number.

21340243720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21340243720 is an abundant number, since it is smaller than the sum of its proper divisors (26675304740).

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

21340243720 is a wasteful number, since it uses less digits than its factorization.

21340243720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 533506104 (or 533506100 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 28.

The spelling of 21340243720 in words is "twenty-one billion, three hundred forty million, two hundred forty-three thousand, seven hundred twenty".