1221157 has 8 divisors (see below), whose sum is σ = 1428416. Its totient is φ = 1022112.

The previous prime is 1221131. The next prime is 1221163. The reversal of 1221157 is 7511221.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1221157 - 2⁷ = 1221029 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221167) 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, 1728 + ... + 2329.

It is an arithmetic number, because the mean of its divisors is an integer number (178552).

2^1221157 is an apocalyptic number.

It is an amenable number.

1221157 is a deficient number, since it is larger than the sum of its proper divisors (207259).

1221157 is an equidigital number, since it uses as much as digits as its factorization.

1221157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4107.

The product of its digits is 140, while the sum is 19.

The square root of 1221157 is about 1105.0597268926. The cubic root of 1221157 is about 106.8867407277.

Adding to 1221157 its reverse (7511221), we get a palindrome (8732378).

Subtracting 1221157 from its reverse (7511221), we obtain a square (6290064 = 2508²).

It can be divided in two parts, 1221 and 157, that added together give a triangular number (1378 = T₅₂).

The spelling of 1221157 in words is "one million, two hundred twenty-one thousand, one hundred fifty-seven".