221605401 has 16 divisors (see below), whose sum is σ = 298080000. Its totient is φ = 146439888.

The previous prime is 221605399. The next prime is 221605409. The reversal of 221605401 is 104506122.

It is not a de Polignac number, because 221605401 - 2¹ = 221605399 is a prime.

It is not an unprimeable number, because it can be changed into a prime (221605409) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 267550 + ... + 268376.

It is an arithmetic number, because the mean of its divisors is an integer number (18630000).

Almost surely, 2^221605401 is an apocalyptic number.

It is an amenable number.

221605401 is a deficient number, since it is larger than the sum of its proper divisors (76474599).

221605401 is a wasteful number, since it uses less digits than its factorization.

221605401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1508.

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 221605401 is about 14886.4166608355. The cubic root of 221605401 is about 605.1459256861.

The spelling of 221605401 in words is "two hundred twenty-one million, six hundred five thousand, four hundred one".