21749667 has 4 divisors (see below), whose sum is σ = 28999560. Its totient is φ = 14499776.

The previous prime is 21749657. The next prime is 21749671. The reversal of 21749667 is 76694712.

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 21749667 - 2⁶ = 21749603 is a prime.

It is a super-2 number, since 2×21749667² = 946096029221778, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21749617) 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, 3624942 + ... + 3624947.

It is an arithmetic number, because the mean of its divisors is an integer number (7249890).

Almost surely, 2^21749667 is an apocalyptic number.

21749667 is a deficient number, since it is larger than the sum of its proper divisors (7249893).

21749667 is an equidigital number, since it uses as much as digits as its factorization.

21749667 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7249892.

The product of its digits is 127008, while the sum is 42.

The square root of 21749667 is about 4663.6538250603. The cubic root of 21749667 is about 279.1370840067.

The spelling of 21749667 in words is "twenty-one million, seven hundred forty-nine thousand, six hundred sixty-seven".