921698681 has 2 divisors, whose sum is σ = 921698682. Its totient is φ = 921698680.

The previous prime is 921698651. The next prime is 921698689. The reversal of 921698681 is 186896129.

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., 754875625 + 166823056 = 27475^2 + 12916^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-921698681 is a prime.

It is a super-2 number, since 2×921698681² = 1699056917114279522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (921698689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 460849340 + 460849341.

It is an arithmetic number, because the mean of its divisors is an integer number (460849341).

Almost surely, 2^921698681 is an apocalyptic number.

It is an amenable number.

921698681 is a deficient number, since it is larger than the sum of its proper divisors (1).

921698681 is an equidigital number, since it uses as much as digits as its factorization.

921698681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 373248, while the sum is 50.

The square root of 921698681 is about 30359.4907895373. The cubic root of 921698681 is about 973.1870517196.

The spelling of 921698681 in words is "nine hundred twenty-one million, six hundred ninety-eight thousand, six hundred eighty-one".