21532691 has 4 divisors (see below), whose sum is σ = 21642192. Its totient is φ = 21423192.

The previous prime is 21532663. The next prime is 21532697. The reversal of 21532691 is 19623512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21532691 - 2¹⁰ = 21531667 is a prime.

It is a super-3 number, since 3×21532691³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21532697) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 54455 + ... + 54848.

It is an arithmetic number, because the mean of its divisors is an integer number (5410548).

Almost surely, 2^21532691 is an apocalyptic number.

21532691 is a deficient number, since it is larger than the sum of its proper divisors (109501).

21532691 is a wasteful number, since it uses less digits than its factorization.

21532691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109500.

The product of its digits is 3240, while the sum is 29.

The square root of 21532691 is about 4640.3330699423. Note that the first 3 decimals coincide. The cubic root of 21532691 is about 278.2057505879.

The spelling of 21532691 in words is "twenty-one million, five hundred thirty-two thousand, six hundred ninety-one".