21505957545 has 32 divisors (see below), whose sum is σ = 35186336640. Its totient is φ = 11213061120.

The previous prime is 21505957531. The next prime is 21505957621. The reversal of 21505957545 is 54575950512.

It is not a de Polignac number, because 21505957545 - 2¹² = 21505953449 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21505957494 and 21505957503.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 93057 + ... + 227313.

It is an arithmetic number, because the mean of its divisors is an integer number (1099573020).

Almost surely, 2^21505957545 is an apocalyptic number.

It is an amenable number.

21505957545 is a deficient number, since it is larger than the sum of its proper divisors (13680379095).

21505957545 is a wasteful number, since it uses less digits than its factorization.

21505957545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134505.

The product of its (nonzero) digits is 1575000, while the sum is 48.

The spelling of 21505957545 in words is "twenty-one billion, five hundred five million, nine hundred fifty-seven thousand, five hundred forty-five".