21980242 has 4 divisors (see below), whose sum is σ = 32970366. Its totient is φ = 10990120.

The previous prime is 21980197. The next prime is 21980243. The reversal of 21980242 is 24208912.

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., 17732521 + 4247721 = 4211^2 + 2061^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21980242.

It is not an unprimeable number, because it can be changed into a prime (21980243) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5495059 + ... + 5495062.

Almost surely, 2^21980242 is an apocalyptic number.

21980242 is a deficient number, since it is larger than the sum of its proper divisors (10990124).

21980242 is a wasteful number, since it uses less digits than its factorization.

21980242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10990123.

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 21980242 is about 4688.3090768421. The cubic root of 21980242 is about 280.1200250732.

It can be divided in two parts, 21980 and 242, that added together give a palindrome (22222).

The spelling of 21980242 in words is "twenty-one million, nine hundred eighty thousand, two hundred forty-two".