28157861621 has 2 divisors, whose sum is σ = 28157861622. Its totient is φ = 28157861620.

The previous prime is 28157861587. The next prime is 28157861647. The reversal of 28157861621 is 12616875182.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27803895025 + 353966596 = 166745^2 + 18814^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28157861621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28157861321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14078930810 + 14078930811.

It is an arithmetic number, because the mean of its divisors is an integer number (14078930811).

Almost surely, 2^28157861621 is an apocalyptic number.

It is an amenable number.

28157861621 is a deficient number, since it is larger than the sum of its proper divisors (1).

28157861621 is an equidigital number, since it uses as much as digits as its factorization.

28157861621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 322560, while the sum is 47.

The spelling of 28157861621 in words is "twenty-eight billion, one hundred fifty-seven million, eight hundred sixty-one thousand, six hundred twenty-one".