64820021 has 8 divisors (see below), whose sum is σ = 75186240. Its totient is φ = 54730368.

The previous prime is 64819999. The next prime is 64820023. The reversal of 64820021 is 12002846.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 64820021 - 2¹⁰ = 64818997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64820023) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 68636 + ... + 69573.

It is an arithmetic number, because the mean of its divisors is an integer number (9398280).

Almost surely, 2^64820021 is an apocalyptic number.

It is an amenable number.

64820021 is a deficient number, since it is larger than the sum of its proper divisors (10366219).

64820021 is a wasteful number, since it uses less digits than its factorization.

64820021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138283.

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 64820021 is about 8051.0881873198. The cubic root of 64820021 is about 401.7011322005.

Adding to 64820021 its reverse (12002846), we get a palindrome (76822867).

The spelling of 64820021 in words is "sixty-four million, eight hundred twenty thousand, twenty-one".