681621701 has 4 divisors (see below), whose sum is σ = 686135904. Its totient is φ = 677107500.

The previous prime is 681621673. The next prime is 681621709. The reversal of 681621701 is 107126186.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 681621701 - 2¹⁰ = 681620677 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 (681621709) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2256875 + ... + 2257176.

It is an arithmetic number, because the mean of its divisors is an integer number (171533976).

Almost surely, 2^681621701 is an apocalyptic number.

It is an amenable number.

681621701 is a deficient number, since it is larger than the sum of its proper divisors (4514203).

681621701 is a wasteful number, since it uses less digits than its factorization.

681621701 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4514202.

The product of its (nonzero) digits is 4032, while the sum is 32.

The square root of 681621701 is about 26107.8858010372. The cubic root of 681621701 is about 880.0644326961.

Adding to 681621701 its reverse (107126186), we get a palindrome (788747887).

The spelling of 681621701 in words is "six hundred eighty-one million, six hundred twenty-one thousand, seven hundred one".