1221021995 has 4 divisors (see below), whose sum is σ = 1465226400. Its totient is φ = 976817592.

The previous prime is 1221021931. The next prime is 1221022013. The reversal of 1221021995 is 5991201221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5991201221 = 2437 ⋅2458433.

It is a cyclic number.

It is not a de Polignac number, because 1221021995 - 2⁶ = 1221021931 is a prime.

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, 122102195 + ... + 122102204.

It is an arithmetic number, because the mean of its divisors is an integer number (366306600).

Almost surely, 2^1221021995 is an apocalyptic number.

1221021995 is a deficient number, since it is larger than the sum of its proper divisors (244204405).

1221021995 is an equidigital number, since it uses as much as digits as its factorization.

1221021995 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244204404.

The product of its (nonzero) digits is 3240, while the sum is 32.

The square root of 1221021995 is about 34943.1251464433. The cubic root of 1221021995 is about 1068.8280162831.

The spelling of 1221021995 in words is "one billion, two hundred twenty-one million, twenty-one thousand, nine hundred ninety-five".