690021481 has 2 divisors, whose sum is σ = 690021482. Its totient is φ = 690021480.

The previous prime is 690021433. The next prime is 690021503. The reversal of 690021481 is 184120096.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 521437225 + 168584256 = 22835^2 + 12984^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-690021481 is a prime.

It is a super-2 number, since 2×690021481² = 952259288482866722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (690021581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345010740 + 345010741.

It is an arithmetic number, because the mean of its divisors is an integer number (345010741).

Almost surely, 2^690021481 is an apocalyptic number.

It is an amenable number.

690021481 is a deficient number, since it is larger than the sum of its proper divisors (1).

690021481 is an equidigital number, since it uses as much as digits as its factorization.

690021481 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 690021481 is about 26268.2599537921. The cubic root of 690021481 is about 883.6647620997.

The spelling of 690021481 in words is "six hundred ninety million, twenty-one thousand, four hundred eighty-one".