1221341691 has 4 divisors (see below), whose sum is σ = 1628455592. Its totient is φ = 814227792.

The previous prime is 1221341687. The next prime is 1221341701. The reversal of 1221341691 is 1961431221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1961431221 = 3 ⋅653810407.

It is not a de Polignac number, because 1221341691 - 2² = 1221341687 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221341651) 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, 203556946 + ... + 203556951.

It is an arithmetic number, because the mean of its divisors is an integer number (407113898).

Almost surely, 2^1221341691 is an apocalyptic number.

1221341691 is a deficient number, since it is larger than the sum of its proper divisors (407113901).

1221341691 is an equidigital number, since it uses as much as digits as its factorization.

1221341691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 407113900.

The product of its digits is 2592, while the sum is 30.

The square root of 1221341691 is about 34947.6993663388. The cubic root of 1221341691 is about 1068.9212906673.

The spelling of 1221341691 in words is "one billion, two hundred twenty-one million, three hundred forty-one thousand, six hundred ninety-one".