15745397821 has 2 divisors, whose sum is σ = 15745397822. Its totient is φ = 15745397820.

The previous prime is 15745397803. The next prime is 15745397827. The reversal of 15745397821 is 12879354751.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9279468900 + 6465928921 = 96330^2 + 80411^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15745397821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15745397827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7872698910 + 7872698911.

It is an arithmetic number, because the mean of its divisors is an integer number (7872698911).

Almost surely, 2^15745397821 is an apocalyptic number.

It is an amenable number.

15745397821 is a deficient number, since it is larger than the sum of its proper divisors (1).

15745397821 is an equidigital number, since it uses as much as digits as its factorization.

15745397821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2116800, while the sum is 52.

The spelling of 15745397821 in words is "fifteen billion, seven hundred forty-five million, three hundred ninety-seven thousand, eight hundred twenty-one".