21473639 has 8 divisors (see below), whose sum is σ = 23868432. Its totient is φ = 19152640.

The previous prime is 21473633. The next prime is 21473657. The reversal of 21473639 is 93637412.

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

It is a cyclic number.

It is not a de Polignac number, because 21473639 - 2⁴ = 21473623 is a prime.

It is a super-2 number, since 2×21473639² = 922234343804642, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21473599 and 21473608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21473633) 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, 17834 + ... + 18999.

It is an arithmetic number, because the mean of its divisors is an integer number (2983554).

Almost surely, 2^21473639 is an apocalyptic number.

21473639 is a deficient number, since it is larger than the sum of its proper divisors (2394793).

21473639 is a wasteful number, since it uses less digits than its factorization.

21473639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36897.

The product of its digits is 27216, while the sum is 35.

The square root of 21473639 is about 4633.9657961621. The cubic root of 21473639 is about 277.9511973750.

The spelling of 21473639 in words is "twenty-one million, four hundred seventy-three thousand, six hundred thirty-nine".