221651601 has 4 divisors (see below), whose sum is σ = 295535472. Its totient is φ = 147767732.

The previous prime is 221651569. The next prime is 221651623. The reversal of 221651601 is 106156122.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 221651601 - 2⁵ = 221651569 is a prime.

It is not an unprimeable number, because it can be changed into a prime (221651641) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36941931 + ... + 36941936.

It is an arithmetic number, because the mean of its divisors is an integer number (73883868).

Almost surely, 2^221651601 is an apocalyptic number.

It is an amenable number.

221651601 is a deficient number, since it is larger than the sum of its proper divisors (73883871).

221651601 is an equidigital number, since it uses as much as digits as its factorization.

221651601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73883870.

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 221651601 is about 14887.9683301651. The cubic root of 221651601 is about 605.1879761039.

The spelling of 221651601 in words is "two hundred twenty-one million, six hundred fifty-one thousand, six hundred one".