1221037655 has 4 divisors (see below), whose sum is σ = 1465245192. Its totient is φ = 976830120.

The previous prime is 1221037637. The next prime is 1221037661. The reversal of 1221037655 is 5567301221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5567301221 = 13001 ⋅428221.

It is not a de Polignac number, because 1221037655 - 2¹⁴ = 1221021271 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 122103761 + ... + 122103770.

It is an arithmetic number, because the mean of its divisors is an integer number (366311298).

Almost surely, 2^1221037655 is an apocalyptic number.

1221037655 is a deficient number, since it is larger than the sum of its proper divisors (244207537).

1221037655 is an equidigital number, since it uses as much as digits as its factorization.

1221037655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244207536.

The product of its (nonzero) digits is 12600, while the sum is 32.

The square root of 1221037655 is about 34943.3492241371. The cubic root of 1221037655 is about 1068.8325856180.

Adding to 1221037655 its reverse (5567301221), we get a palindrome (6788338876).

The spelling of 1221037655 in words is "one billion, two hundred twenty-one million, thirty-seven thousand, six hundred fifty-five".