21780722 has 4 divisors (see below), whose sum is σ = 32671086. Its totient is φ = 10890360.

The previous prime is 21780713. The next prime is 21780727. The reversal of 21780722 is 22708712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 11015761 + 10764961 = 3319^2 + 3281^2 .

It is not an unprimeable number, because it can be changed into a prime (21780727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5445179 + ... + 5445182.

Almost surely, 2^21780722 is an apocalyptic number.

21780722 is a deficient number, since it is larger than the sum of its proper divisors (10890364).

21780722 is a wasteful number, since it uses less digits than its factorization.

21780722 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10890363.

The product of its (nonzero) digits is 3136, while the sum is 29.

The square root of 21780722 is about 4666.9821083865. The cubic root of 21780722 is about 279.2698749996.

The spelling of 21780722 in words is "twenty-one million, seven hundred eighty thousand, seven hundred twenty-two".