221001581 has 8 divisors (see below), whose sum is σ = 234368640. Its totient is φ = 207675328.

The previous prime is 221001541. The next prime is 221001589. The reversal of 221001581 is 185100122.

221001581 = 2533² + 2534² + ... + 2566².

It is a happy number.

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 221001581 - 2¹⁴ = 220985197 is a prime.

It is a super-2 number, since 2×221001581² = 97683397608999122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221001589) 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, 1340 + ... + 21066.

It is an arithmetic number, because the mean of its divisors is an integer number (29296080).

Almost surely, 2^221001581 is an apocalyptic number.

It is an amenable number.

221001581 is a deficient number, since it is larger than the sum of its proper divisors (13367059).

221001581 is a wasteful number, since it uses less digits than its factorization.

221001581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20403.

The product of its (nonzero) digits is 160, while the sum is 20.

The square root of 221001581 is about 14866.1219220078. The cubic root of 221001581 is about 604.5958013228.

The spelling of 221001581 in words is "two hundred twenty-one million, one thousand, five hundred eighty-one".