208421638 has 4 divisors (see below), whose sum is σ = 312632460. Its totient is φ = 104210818.

The previous prime is 208421617. The next prime is 208421651. The reversal of 208421638 is 836124802.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 52105408 + ... + 52105411.

It is an arithmetic number, because the mean of its divisors is an integer number (78158115).

Almost surely, 2^208421638 is an apocalyptic number.

208421638 is a deficient number, since it is larger than the sum of its proper divisors (104210822).

208421638 is a wasteful number, since it uses less digits than its factorization.

208421638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104210821.

The product of its (nonzero) digits is 18432, while the sum is 34.

The square root of 208421638 is about 14436.8153690487. The cubic root of 208421638 is about 592.8992963246.

The spelling of 208421638 in words is "two hundred eight million, four hundred twenty-one thousand, six hundred thirty-eight".