6991553 has 2 divisors, whose sum is σ = 6991554. Its totient is φ = 6991552.

The previous prime is 6991549. The next prime is 6991571. The reversal of 6991553 is 3551996.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4765489 + 2226064 = 2183^2 + 1492^2 .

It is a cyclic number.

It is not a de Polignac number, because 6991553 - 2² = 6991549 is a prime.

It is not a weakly prime, because it can be changed into another prime (6991513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3495776 + 3495777.

It is an arithmetic number, because the mean of its divisors is an integer number (3495777).

Almost surely, 2^6991553 is an apocalyptic number.

It is an amenable number.

6991553 is a deficient number, since it is larger than the sum of its proper divisors (1).

6991553 is an equidigital number, since it uses as much as digits as its factorization.

6991553 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36450, while the sum is 38.

The square root of 6991553 is about 2644.1544962426. The cubic root of 6991553 is about 191.2161419266.

The spelling of 6991553 in words is "six million, nine hundred ninety-one thousand, five hundred fifty-three".