1621128038721 has 32 divisors (see below), whose sum is σ = 2221699294080. Its totient is φ = 1051055947776.

The previous prime is 1621128038653. The next prime is 1621128038723. The reversal of 1621128038721 is 1278308211261.

It is not a de Polignac number, because 1621128038721 - 2²⁷ = 1620993820993 is a prime.

It is a super-2 number, since 2×1621128038721² (a number of 25 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1621128038723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 45600265 + ... + 45635801.

It is an arithmetic number, because the mean of its divisors is an integer number (69428102940).

Almost surely, 2^{1621128038721} is an apocalyptic number.

It is an amenable number.

1621128038721 is a deficient number, since it is larger than the sum of its proper divisors (600571255359).

1621128038721 is a wasteful number, since it uses less digits than its factorization.

1621128038721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38353.

The product of its (nonzero) digits is 64512, while the sum is 42.

The spelling of 1621128038721 in words is "one trillion, six hundred twenty-one billion, one hundred twenty-eight million, thirty-eight thousand, seven hundred twenty-one".