21772091 has 4 divisors (see below), whose sum is σ = 23751384. Its totient is φ = 19792800.

The previous prime is 21772067. The next prime is 21772097. The reversal of 21772091 is 19027712.

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 21772091 - 2²² = 17577787 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21772097) 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, 989630 + ... + 989651.

It is an arithmetic number, because the mean of its divisors is an integer number (5937846).

Almost surely, 2^21772091 is an apocalyptic number.

21772091 is a deficient number, since it is larger than the sum of its proper divisors (1979293).

21772091 is a wasteful number, since it uses less digits than its factorization.

21772091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1979292.

The product of its (nonzero) digits is 1764, while the sum is 29.

The square root of 21772091 is about 4666.0573292663. The cubic root of 21772091 is about 279.2329815678.

The spelling of 21772091 in words is "twenty-one million, seven hundred seventy-two thousand, ninety-one".