21772051 has 4 divisors (see below), whose sum is σ = 24882352. Its totient is φ = 18661752.

The previous prime is 21772033. The next prime is 21772057. The reversal of 21772051 is 15027712.

It is a happy number.

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 21772051 - 2⁹ = 21771539 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21772057) 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, 1555140 + ... + 1555153.

It is an arithmetic number, because the mean of its divisors is an integer number (6220588).

Almost surely, 2^21772051 is an apocalyptic number.

21772051 is a deficient number, since it is larger than the sum of its proper divisors (3110301).

21772051 is an equidigital number, since it uses as much as digits as its factorization.

21772051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3110300.

The product of its (nonzero) digits is 980, while the sum is 25.

The square root of 21772051 is about 4666.0530429904. The cubic root of 21772051 is about 279.2328105640.

Adding to 21772051 its reverse (15027712), we get a palindrome (36799763).

The spelling of 21772051 in words is "twenty-one million, seven hundred seventy-two thousand, fifty-one".