21264021599 has 4 divisors (see below), whose sum is σ = 21502943280. Its totient is φ = 21025099920.

The previous prime is 21264021557. The next prime is 21264021629. The reversal of 21264021599 is 99512046212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21264021599 - 2⁸ = 21264021343 is a prime.

It is a super-2 number, since 2×21264021599² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21264021199) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 119460707 + ... + 119460884.

It is an arithmetic number, because the mean of its divisors is an integer number (5375735820).

Almost surely, 2^21264021599 is an apocalyptic number.

21264021599 is a deficient number, since it is larger than the sum of its proper divisors (238921681).

21264021599 is an equidigital number, since it uses as much as digits as its factorization.

21264021599 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 238921680.

The product of its (nonzero) digits is 77760, while the sum is 41.

The spelling of 21264021599 in words is "twenty-one billion, two hundred sixty-four million, twenty-one thousand, five hundred ninety-nine".