690021 has 12 divisors (see below), whose sum is σ = 1020448. Its totient is φ = 449064.

The previous prime is 689987. The next prime is 690037. The reversal of 690021 is 120096.

690021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 690021 - 2⁶ = 689957 is a prime.

It is a super-2 number, since 2×690021² = 952257960882, which contains 22 as substring.

It is a Duffinian number.

690021 is a lucky number.

It is a nialpdrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 689976 and 690003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (690721) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 505 + ... + 1278.

2⁶⁹⁰⁰²¹ is an apocalyptic number.

It is an amenable number.

690021 is a deficient number, since it is larger than the sum of its proper divisors (330427).

690021 is a wasteful number, since it uses less digits than its factorization.

690021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1832 (or 1829 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 18.

The square root of 690021 is about 830.6750267102. The cubic root of 690021 is about 88.3664556771.

The spelling of 690021 in words is "six hundred ninety thousand, twenty-one".