21990467 has 4 divisors (see below), whose sum is σ = 23147880. Its totient is φ = 20833056.

The previous prime is 21990457. The next prime is 21990487. The reversal of 21990467 is 76409912.

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 21990467 - 2¹⁸ = 21728323 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21990467.

It is not an unprimeable number, because it can be changed into a prime (21990457) 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, 578678 + ... + 578715.

It is an arithmetic number, because the mean of its divisors is an integer number (5786970).

Almost surely, 2^21990467 is an apocalyptic number.

21990467 is a deficient number, since it is larger than the sum of its proper divisors (1157413).

21990467 is a wasteful number, since it uses less digits than its factorization.

21990467 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1157412.

The product of its (nonzero) digits is 27216, while the sum is 38.

The square root of 21990467 is about 4689.3994284983. The cubic root of 21990467 is about 280.1634547320.

The spelling of 21990467 in words is "twenty-one million, nine hundred ninety thousand, four hundred sixty-seven".