64121821 has 4 divisors (see below), whose sum is σ = 64505952. Its totient is φ = 63737692.

The previous prime is 64121819. The next prime is 64121831. The reversal of 64121821 is 12812146.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 64121821 - 2¹ = 64121819 is a prime.

It is a super-2 number, since 2×64121821² = 8223215856712082, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64121801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 191815 + ... + 192148.

It is an arithmetic number, because the mean of its divisors is an integer number (16126488).

Almost surely, 2^64121821 is an apocalyptic number.

It is an amenable number.

64121821 is a deficient number, since it is larger than the sum of its proper divisors (384131).

64121821 is a wasteful number, since it uses less digits than its factorization.

64121821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 384130.

The product of its digits is 768, while the sum is 25.

The square root of 64121821 is about 8007.6101928103. The cubic root of 64121821 is about 400.2536328919.

Adding to 64121821 its reverse (12812146), we get a palindrome (76933967).

The spelling of 64121821 in words is "sixty-four million, one hundred twenty-one thousand, eight hundred twenty-one".