69640821 has 12 divisors (see below), whose sum is σ = 100682400. Its totient is φ = 46385640.

The previous prime is 69640817. The next prime is 69640841. The reversal of 69640821 is 12804696.

69640821 is a `hidden beast` number, since 6 + 9 + 640 + 8 + 2 + 1 = 666.

It is not a de Polignac number, because 69640821 - 2² = 69640817 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (69640841) 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, 9826 + ... + 15356.

It is an arithmetic number, because the mean of its divisors is an integer number (8390200).

Almost surely, 2^69640821 is an apocalyptic number.

It is an amenable number.

69640821 is a deficient number, since it is larger than the sum of its proper divisors (31041579).

69640821 is a wasteful number, since it uses less digits than its factorization.

69640821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6936 (or 6933 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 69640821 is about 8345.1076086531. The cubic root of 69640821 is about 411.4224260718.

The spelling of 69640821 in words is "sixty-nine million, six hundred forty thousand, eight hundred twenty-one".