821374252209 has 81 divisors (see below), whose sum is σ = 1396995779673. Its totient is φ = 463690546704.

The previous prime is 821374252051. The next prime is 821374252217. The reversal of 821374252209 is 902252473128.

The square root of 821374252209 is 906297.

It is a perfect power (a square), and thus also a powerful number.

821374252209 is a `hidden beast` number, since 8 + 2 + 1 + 374 + 252 + 20 + 9 = 666.

It is not a de Polignac number, because 821374252209 - 2¹⁹ = 821373727921 is a prime.

It is not an unprimeable number, because it can be changed into a prime (821374252609) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 1960320202 + ... + 1960320620.

Almost surely, 2^821374252209 is an apocalyptic number.

821374252209 is the 906297-th square number.

821374252209 is the 453149-th centered octagonal number.

It is an amenable number.

821374252209 is a deficient number, since it is larger than the sum of its proper divisors (575621527464).

821374252209 is an equidigital number, since it uses as much as digits as its factorization.

821374252209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1064 (or 532 counting only the distinct ones).

The product of its (nonzero) digits is 483840, while the sum is 45.

The spelling of 821374252209 in words is "eight hundred twenty-one billion, three hundred seventy-four million, two hundred fifty-two thousand, two hundred nine".