21931669 has 4 divisors (see below), whose sum is σ = 21993120. Its totient is φ = 21870220.

The previous prime is 21931633. The next prime is 21931691. The reversal of 21931669 is 96613912.

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 21931669 - 2⁷ = 21931541 is a prime.

It is a super-2 number, since 2×21931669² = 961996210251122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21931619) 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 3 ways as a sum of consecutive naturals, for example, 30187 + ... + 30904.

It is an arithmetic number, because the mean of its divisors is an integer number (5498280).

Almost surely, 2^21931669 is an apocalyptic number.

It is an amenable number.

21931669 is a deficient number, since it is larger than the sum of its proper divisors (61451).

21931669 is an equidigital number, since it uses as much as digits as its factorization.

21931669 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61450.

The product of its digits is 17496, while the sum is 37.

The square root of 21931669 is about 4683.1259859201. The cubic root of 21931669 is about 279.9135319736.

The spelling of 21931669 in words is "twenty-one million, nine hundred thirty-one thousand, six hundred sixty-nine".