21535291 has 12 divisors (see below), whose sum is σ = 23074416. Its totient is φ = 20060480.

The previous prime is 21535289. The next prime is 21535309. The reversal of 21535291 is 19253512.

It is not a de Polignac number, because 21535291 - 2¹ = 21535289 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21535231) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 38385 + ... + 38941.

It is an arithmetic number, because the mean of its divisors is an integer number (1922868).

Almost surely, 2^21535291 is an apocalyptic number.

21535291 is a deficient number, since it is larger than the sum of its proper divisors (1539125).

21535291 is an equidigital number, since it uses as much as digits as its factorization.

21535291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 662 (or 621 counting only the distinct ones).

The product of its digits is 2700, while the sum is 28.

The square root of 21535291 is about 4640.6132137897. The cubic root of 21535291 is about 278.2169476068.

The spelling of 21535291 in words is "twenty-one million, five hundred thirty-five thousand, two hundred ninety-one".