1621432551461 has 4 divisors (see below), whose sum is σ = 1622805484524. Its totient is φ = 1620059618400.

The previous prime is 1621432551367. The next prime is 1621432551499. The reversal of 1621432551461 is 1641552341261.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1541555660836 + 79876890625 = 1241594^2 + 282625^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1621432551461 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621432551161) 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, 686464760 + ... + 686467121.

It is an arithmetic number, because the mean of its divisors is an integer number (405701371131).

Almost surely, 2^{1621432551461} is an apocalyptic number.

It is an amenable number.

1621432551461 is a deficient number, since it is larger than the sum of its proper divisors (1372933063).

1621432551461 is a wasteful number, since it uses less digits than its factorization.

1621432551461 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1372933062.

The product of its digits is 172800, while the sum is 41.

The spelling of 1621432551461 in words is "one trillion, six hundred twenty-one billion, four hundred thirty-two million, five hundred fifty-one thousand, four hundred sixty-one".