821664951 has 32 divisors (see below), whose sum is σ = 1160552448. Its totient is φ = 516318720.

The previous prime is 821664929. The next prime is 821664959. The reversal of 821664951 is 159466128.

It is not a de Polignac number, because 821664951 - 2⁵ = 821664919 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821664959) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1385311 + ... + 1385903.

It is an arithmetic number, because the mean of its divisors is an integer number (36267264).

Almost surely, 2^821664951 is an apocalyptic number.

821664951 is a deficient number, since it is larger than the sum of its proper divisors (338887497).

821664951 is a wasteful number, since it uses less digits than its factorization.

821664951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 991.

The product of its digits is 103680, while the sum is 42.

The square root of 821664951 is about 28664.6986902008. The cubic root of 821664951 is about 936.6232209402.

The spelling of 821664951 in words is "eight hundred twenty-one million, six hundred sixty-four thousand, nine hundred fifty-one".