697779921 has 24 divisors (see below), whose sum is σ = 991839520. Its totient is φ = 435148416.

The previous prime is 697779919. The next prime is 697779923. The reversal of 697779921 is 129977796.

697779921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (697779919) and next prime (697779923).

It is not a de Polignac number, because 697779921 - 2¹ = 697779919 is a prime.

It is a Smith number, since the sum of its digits (57) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (57).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (697779923) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 391785 + ... + 393561.

Almost surely, 2^697779921 is an apocalyptic number.

It is an amenable number.

697779921 is a deficient number, since it is larger than the sum of its proper divisors (294059599).

697779921 is a wasteful number, since it uses less digits than its factorization.

697779921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1965 (or 1882 counting only the distinct ones).

The product of its digits is 3000564, while the sum is 57.

The square root of 697779921 is about 26415.5242423844. The cubic root of 697779921 is about 886.9643328664.

The spelling of 697779921 in words is "six hundred ninety-seven million, seven hundred seventy-nine thousand, nine hundred twenty-one".