1221495951221 has 24 divisors (see below), whose sum is σ = 1597015768320. Its totient is φ = 909607825152.

The previous prime is 1221495951209. The next prime is 1221495951223. The reversal of 1221495951221 is 1221595941221.

It is not a de Polignac number, because 1221495951221 - 2²⁶ = 1221428842357 is a prime.

It is a super-2 number, since 2×1221495951221² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221495951223) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 23196941 + ... + 23249538.

It is an arithmetic number, because the mean of its divisors is an integer number (66542323680).

Almost surely, 2^{1221495951221} is an apocalyptic number.

It is an amenable number.

1221495951221 is a deficient number, since it is larger than the sum of its proper divisors (375519817099).

1221495951221 is a wasteful number, since it uses less digits than its factorization.

1221495951221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46446533 (or 46446516 counting only the distinct ones).

The product of its digits is 129600, while the sum is 44.

The spelling of 1221495951221 in words is "one trillion, two hundred twenty-one billion, four hundred ninety-five million, nine hundred fifty-one thousand, two hundred twenty-one".