21516769 has 4 divisors (see below), whose sum is σ = 21881520. Its totient is φ = 21152020.

The previous prime is 21516767. The next prime is 21516791. The reversal of 21516769 is 96761512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21516769 - 2¹ = 21516767 is a prime.

It is a super-2 number, since 2×21516769² = 925942696398722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21516767) 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, 182287 + ... + 182404.

It is an arithmetic number, because the mean of its divisors is an integer number (5470380).

Almost surely, 2^21516769 is an apocalyptic number.

It is an amenable number.

21516769 is a deficient number, since it is larger than the sum of its proper divisors (364751).

21516769 is an equidigital number, since it uses as much as digits as its factorization.

21516769 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 364750.

The product of its digits is 22680, while the sum is 37.

The square root of 21516769 is about 4638.6171430718. The cubic root of 21516769 is about 278.1371620991.

The spelling of 21516769 in words is "twenty-one million, five hundred sixteen thousand, seven hundred sixty-nine".