900806521 has 2 divisors, whose sum is σ = 900806522. Its totient is φ = 900806520.

The previous prime is 900806503. The next prime is 900806539. The reversal of 900806521 is 125608009.

It is a balanced prime because it is at equal distance from previous prime (900806503) and next prime (900806539).

It can be written as a sum of positive squares in only one way, i.e., 565916521 + 334890000 = 23789^2 + 18300^2 .

It is a cyclic number.

It is not a de Polignac number, because 900806521 - 2⁷ = 900806393 is a prime.

It is a super-2 number, since 2×900806521² = 1622904776552246882, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (900800521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 450403260 + 450403261.

It is an arithmetic number, because the mean of its divisors is an integer number (450403261).

Almost surely, 2^900806521 is an apocalyptic number.

It is an amenable number.

900806521 is a deficient number, since it is larger than the sum of its proper divisors (1).

900806521 is an equidigital number, since it uses as much as digits as its factorization.

900806521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4320, while the sum is 31.

The square root of 900806521 is about 30013.4390065517. The cubic root of 900806521 is about 965.7777012637. Note that the first 4 decimals are identical.

The spelling of 900806521 in words is "nine hundred million, eight hundred six thousand, five hundred twenty-one".