20521437859 has 4 divisors (see below), whose sum is σ = 22100010016. Its totient is φ = 18942865704.

The previous prime is 20521437857. The next prime is 20521437869. The reversal of 20521437859 is 95873412502.

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 20521437859 - 2¹ = 20521437857 is a prime.

It is a super-2 number, since 2×20521437859² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20521437857) 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, 789286059 + ... + 789286084.

It is an arithmetic number, because the mean of its divisors is an integer number (5525002504).

Almost surely, 2^20521437859 is an apocalyptic number.

20521437859 is a deficient number, since it is larger than the sum of its proper divisors (1578572157).

20521437859 is a wasteful number, since it uses less digits than its factorization.

20521437859 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1578572156.

The product of its (nonzero) digits is 604800, while the sum is 46.

The spelling of 20521437859 in words is "twenty billion, five hundred twenty-one million, four hundred thirty-seven thousand, eight hundred fifty-nine".