21520203541 has 8 divisors (see below), whose sum is σ = 21578763960. Its totient is φ = 21461715648.

The previous prime is 21520203517. The next prime is 21520203571. The reversal of 21520203541 is 14530202512.

It can be written as a sum of positive squares in 4 ways, for example, as 5269308100 + 16250895441 = 72590^2 + 127479^2 .

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 21520203541 - 2⁷ = 21520203413 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21520203511) 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, 604875 + ... + 639463.

It is an arithmetic number, because the mean of its divisors is an integer number (2697345495).

Almost surely, 2^21520203541 is an apocalyptic number.

It is an amenable number.

21520203541 is a deficient number, since it is larger than the sum of its proper divisors (58560419).

21520203541 is a wasteful number, since it uses less digits than its factorization.

21520203541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36263.

The product of its (nonzero) digits is 2400, while the sum is 25.

The spelling of 21520203541 in words is "twenty-one billion, five hundred twenty million, two hundred three thousand, five hundred forty-one".