20721434 has 8 divisors (see below), whose sum is σ = 31101780. Its totient is φ = 10354176.

The previous prime is 20721433. The next prime is 20721439. The reversal of 20721434 is 43412702.

It can be written as a sum of positive squares in 2 ways, for example, as 20675209 + 46225 = 4547^2 + 215^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (20721433) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3452 + ... + 7304.

Almost surely, 2^20721434 is an apocalyptic number.

20721434 is a deficient number, since it is larger than the sum of its proper divisors (10380346).

20721434 is a wasteful number, since it uses less digits than its factorization.

20721434 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6544.

The product of its (nonzero) digits is 1344, while the sum is 23.

The square root of 20721434 is about 4552.0801838280. The cubic root of 20721434 is about 274.6670747970.

The spelling of 20721434 in words is "twenty million, seven hundred twenty-one thousand, four hundred thirty-four".