521100021 has 8 divisors (see below), whose sum is σ = 748246240. Its totient is φ = 320676912.

The previous prime is 521100017. The next prime is 521100059. The reversal of 521100021 is 120001125.

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

It is not a de Polignac number, because 521100021 - 2² = 521100017 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 (521100091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6680731 + ... + 6680808.

It is an arithmetic number, because the mean of its divisors is an integer number (93530780).

Almost surely, 2^521100021 is an apocalyptic number.

It is an amenable number.

521100021 is a deficient number, since it is larger than the sum of its proper divisors (227146219).

521100021 is a wasteful number, since it uses less digits than its factorization.

521100021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13361555.

The product of its (nonzero) digits is 20, while the sum is 12.

The square root of 521100021 is about 22827.6153156654. The cubic root of 521100021 is about 804.7117885987.

Adding to 521100021 its reverse (120001125), we get a palindrome (641101146).

The spelling of 521100021 in words is "five hundred twenty-one million, one hundred thousand, twenty-one".