21268723720 has 16 divisors (see below), whose sum is σ = 47854628460. Its totient is φ = 8507489472.

The previous prime is 21268723717. The next prime is 21268723757. The reversal of 21268723720 is 2732786212.

It can be written as a sum of positive squares in 2 ways, for example, as 20415265924 + 853457796 = 142882^2 + 29214^2 .

It is a Harshad number since it is a multiple of its sum of digits (40), and also a Moran number because the ratio is a prime number: 531718093 = 21268723720 / (2 + 1 + 2 + 6 + 8 + 7 + 2 + 3 + 7 + 2 + 0).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 265859007 + ... + 265859086.

Almost surely, 2^21268723720 is an apocalyptic number.

21268723720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21268723720 is an abundant number, since it is smaller than the sum of its proper divisors (26585904740).

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

21268723720 is a wasteful number, since it uses less digits than its factorization.

21268723720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 531718104 (or 531718100 counting only the distinct ones).

The product of its (nonzero) digits is 112896, while the sum is 40.

The spelling of 21268723720 in words is "twenty-one billion, two hundred sixty-eight million, seven hundred twenty-three thousand, seven hundred twenty".