21989535 has 16 divisors (see below), whose sum is σ = 35263104. Its totient is φ = 11701152.

The previous prime is 21989521. The next prime is 21989537. The reversal of 21989535 is 53598912.

It is not a de Polignac number, because 21989535 - 2⁴ = 21989519 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21989537) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6444 + ... + 9246.

It is an arithmetic number, because the mean of its divisors is an integer number (2203944).

Almost surely, 2^21989535 is an apocalyptic number.

21989535 is a deficient number, since it is larger than the sum of its proper divisors (13273569).

21989535 is a wasteful number, since it uses less digits than its factorization.

21989535 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3334.

The product of its digits is 97200, while the sum is 42.

The square root of 21989535 is about 4689.3000543791. The cubic root of 21989535 is about 280.1594967135.

The spelling of 21989535 in words is "twenty-one million, nine hundred eighty-nine thousand, five hundred thirty-five".