21190639 has 8 divisors (see below), whose sum is σ = 21958272. Its totient is φ = 20428320.

The previous prime is 21190627. The next prime is 21190661. The reversal of 21190639 is 93609112.

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 21190639 - 2¹⁷ = 21059567 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21190639.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21190679) 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, 7917 + ... + 10249.

It is an arithmetic number, because the mean of its divisors is an integer number (2744784).

Almost surely, 2^21190639 is an apocalyptic number.

21190639 is a deficient number, since it is larger than the sum of its proper divisors (767633).

21190639 is a wasteful number, since it uses less digits than its factorization.

21190639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2657.

The product of its (nonzero) digits is 2916, while the sum is 31.

The square root of 21190639 is about 4603.3291214077. The cubic root of 21190639 is about 276.7247588535.

The spelling of 21190639 in words is "twenty-one million, one hundred ninety thousand, six hundred thirty-nine".