1621505149991 has 2 divisors, whose sum is σ = 1621505149992. Its totient is φ = 1621505149990.

The previous prime is 1621505149879. The next prime is 1621505150053. The reversal of 1621505149991 is 1999415051261.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1621505149991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1621505149591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 810752574995 + 810752574996.

It is an arithmetic number, because the mean of its divisors is an integer number (810752574996).

Almost surely, 2^{1621505149991} is an apocalyptic number.

1621505149991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1621505149991 is an equidigital number, since it uses as much as digits as its factorization.

1621505149991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 874800, while the sum is 53.

The spelling of 1621505149991 in words is "one trillion, six hundred twenty-one billion, five hundred five million, one hundred forty-nine thousand, nine hundred ninety-one".