21292505 has 16 divisors (see below), whose sum is σ = 28406784. Its totient is φ = 15215040.

The previous prime is 21292487. The next prime is 21292507. The reversal of 21292505 is 50529212.

It is not a de Polignac number, because 21292505 - 2⁶ = 21292441 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21292507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3269 + ... + 7298.

It is an arithmetic number, because the mean of its divisors is an integer number (1775424).

Almost surely, 2^21292505 is an apocalyptic number.

It is an amenable number.

21292505 is a deficient number, since it is larger than the sum of its proper divisors (7114279).

21292505 is a wasteful number, since it uses less digits than its factorization.

21292505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10616.

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 21292505 is about 4614.3802400756. The cubic root of 21292505 is about 277.1674668413.

The spelling of 21292505 in words is "twenty-one million, two hundred ninety-two thousand, five hundred five".