21639346 has 4 divisors (see below), whose sum is σ = 32459022. Its totient is φ = 10819672.

The previous prime is 21639341. The next prime is 21639361. The reversal of 21639346 is 64393612.

It is a happy number.

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., 21520321 + 119025 = 4639^2 + 345^2 .

It is a super-2 number, since 2×21639346² = 936522590615432, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21639341) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5409835 + ... + 5409838.

Almost surely, 2^21639346 is an apocalyptic number.

21639346 is a deficient number, since it is larger than the sum of its proper divisors (10819676).

21639346 is a wasteful number, since it uses less digits than its factorization.

21639346 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10819675.

The product of its digits is 23328, while the sum is 34.

The square root of 21639346 is about 4651.8110451737. The cubic root of 21639346 is about 278.6643274022.

The spelling of 21639346 in words is "twenty-one million, six hundred thirty-nine thousand, three hundred forty-six".