1621225216973 has 4 divisors (see below), whose sum is σ = 1622609697408. Its totient is φ = 1619840736540.

The previous prime is 1621225216969. The next prime is 1621225217047. The reversal of 1621225216973 is 3796125221261.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1621225216973 - 2² = 1621225216969 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621225216873) 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, 692238461 + ... + 692240802.

It is an arithmetic number, because the mean of its divisors is an integer number (405652424352).

Almost surely, 2^{1621225216973} is an apocalyptic number.

It is an amenable number.

1621225216973 is a deficient number, since it is larger than the sum of its proper divisors (1384480435).

1621225216973 is a wasteful number, since it uses less digits than its factorization.

1621225216973 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1384480434.

The product of its digits is 544320, while the sum is 47.

The spelling of 1621225216973 in words is "one trillion, six hundred twenty-one billion, two hundred twenty-five million, two hundred sixteen thousand, nine hundred seventy-three".