821808972 has 36 divisors (see below), whose sum is σ = 2078713000. Its totient is φ = 273756672.

The previous prime is 821808877. The next prime is 821808973. The reversal of 821808972 is 279808128.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (36).

It is not an unprimeable number, because it can be changed into a prime (821808973) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 55404 + ... + 68652.

Almost surely, 2^821808972 is an apocalyptic number.

It is an amenable number.

821808972 is an abundant number, since it is smaller than the sum of its proper divisors (1256904028).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

821808972 is a wasteful number, since it uses less digits than its factorization.

821808972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14982 (or 14977 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 45.

The square root of 821808972 is about 28667.2107467748. The cubic root of 821808972 is about 936.6779413516.

The spelling of 821808972 in words is "eight hundred twenty-one million, eight hundred eight thousand, nine hundred seventy-two".