21387307536 has 135 divisors (see below), whose sum is σ = 69666977133. Its totient is φ = 6107149440.

The previous prime is 21387307519. The next prime is 21387307537. The reversal of 21387307536 is 63570378312.

The square root of 21387307536 is 146244.

It is a perfect power (a square), and thus also a powerful number.

21387307536 is a `hidden beast` number, since 2 + 1 + 3 + 87 + 30 + 7 + 536 = 666.

It can be written as a sum of positive squares in only one way, i.e., 24561936 + 21362745600 = 4956^2 + 146160^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21387307491 and 21387307500.

It is not an unprimeable number, because it can be changed into a prime (21387307537) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 12283626 + ... + 12285366.

Almost surely, 2^21387307536 is an apocalyptic number.

21387307536 is the 146244-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21387307536

21387307536 is an abundant number, since it is smaller than the sum of its proper divisors (48279669597).

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

21387307536 is an equidigital number, since it uses as much as digits as its factorization.

21387307536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3510 (or 1753 counting only the distinct ones).

The product of its (nonzero) digits is 635040, while the sum is 45.

The spelling of 21387307536 in words is "twenty-one billion, three hundred eighty-seven million, three hundred seven thousand, five hundred thirty-six".