21772806 has 16 divisors (see below), whose sum is σ = 47504448. Its totient is φ = 6597800.

The previous prime is 21772787. The next prime is 21772811. The reversal of 21772806 is 60827712.

It is a super-2 number, since 2×21772806² = 948110162227272, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 164880 + ... + 165011.

It is an arithmetic number, because the mean of its divisors is an integer number (2969028).

Almost surely, 2^21772806 is an apocalyptic number.

21772806 is an abundant number, since it is smaller than the sum of its proper divisors (25731642).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21772806 is a wasteful number, since it uses less digits than its factorization.

21772806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 329907.

The product of its (nonzero) digits is 9408, while the sum is 33.

The square root of 21772806 is about 4666.1339457842. The cubic root of 21772806 is about 279.2360382241.

It can be divided in two parts, 21772 and 806, that added together give a triangular number (22578 = T₂₁₂).

The spelling of 21772806 in words is "twenty-one million, seven hundred seventy-two thousand, eight hundred six".