21439998 has 16 divisors (see below), whose sum is σ = 47644560. Its totient is φ = 7146648.

The previous prime is 21439997. The next prime is 21440017. The reversal of 21439998 is 89993412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21439997) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 198465 + ... + 198572.

It is an arithmetic number, because the mean of its divisors is an integer number (2977785).

Almost surely, 2^21439998 is an apocalyptic number.

21439998 is an abundant number, since it is smaller than the sum of its proper divisors (26204562).

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

21439998 is a wasteful number, since it uses less digits than its factorization.

21439998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 397048 (or 397042 counting only the distinct ones).

The product of its digits is 139968, while the sum is 45.

The square root of 21439998 is about 4630.3345451490. The cubic root of 21439998 is about 277.8059736831.

It can be divided in two parts, 2 and 1439998, that added together give a square (1440000 = 1200²).

The spelling of 21439998 in words is "twenty-one million, four hundred thirty-nine thousand, nine hundred ninety-eight".