21439193 has 6 divisors (see below), whose sum is σ = 22720554. Its totient is φ = 20160096.

The previous prime is 21439183. The next prime is 21439199. The reversal of 21439193 is 39193412.

It can be written as a sum of positive squares in only one way, i.e., 20178064 + 1261129 = 4492^2 + 1123^2 .

It is not a de Polignac number, because 21439193 - 2¹⁶ = 21373657 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21439199) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 18530 + ... + 19652.

It is an arithmetic number, because the mean of its divisors is an integer number (3786759).

Almost surely, 2^21439193 is an apocalyptic number.

It is an amenable number.

21439193 is a deficient number, since it is larger than the sum of its proper divisors (1281361).

21439193 is an frugal number, since it uses more digits than its factorization.

21439193 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2263 (or 1140 counting only the distinct ones).

The product of its digits is 5832, while the sum is 32.

The square root of 21439193 is about 4630.2476175686. The cubic root of 21439193 is about 277.8024967454.

The spelling of 21439193 in words is "twenty-one million, four hundred thirty-nine thousand, one hundred ninety-three".