1221566 has 4 divisors (see below), whose sum is σ = 1832352. Its totient is φ = 610782.

The previous prime is 1221559. The next prime is 1221589. The reversal of 1221566 is 6651221.

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

It is an Ulam number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 305390 + ... + 305393.

It is an arithmetic number, because the mean of its divisors is an integer number (458088).

2^1221566 is an apocalyptic number.

1221566 is a deficient number, since it is larger than the sum of its proper divisors (610786).

1221566 is an equidigital number, since it uses as much as digits as its factorization.

1221566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 610785.

The product of its digits is 720, while the sum is 23.

The square root of 1221566 is about 1105.2447692706. The cubic root of 1221566 is about 106.8986725260.

Adding to 1221566 its reverse (6651221), we get a palindrome (7872787).

The spelling of 1221566 in words is "one million, two hundred twenty-one thousand, five hundred sixty-six".