21520890001 has 8 divisors (see below), whose sum is σ = 23180812200. Its totient is φ = 19861606272.

The previous prime is 21520889969. The next prime is 21520890023. The reversal of 21520890001 is 10009802512.

It is a Cunningham number, because it is equal to 146700²+1.

It can be written as a sum of positive squares in 4 ways, for example, as 3183667776 + 18337222225 = 56424^2 + 135415^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21520890001 - 2⁵ = 21520889969 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21523890001) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 88426 + ... + 225523.

It is an arithmetic number, because the mean of its divisors is an integer number (2897601525).

Almost surely, 2^21520890001 is an apocalyptic number.

It is an amenable number.

21520890001 is a deficient number, since it is larger than the sum of its proper divisors (1659922199).

21520890001 is a wasteful number, since it uses less digits than its factorization.

21520890001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 319235.

The product of its (nonzero) digits is 1440, while the sum is 28.

The spelling of 21520890001 in words is "twenty-one billion, five hundred twenty million, eight hundred ninety thousand, one".