691221585949 has 16 divisors (see below), whose sum is σ = 739592573760. Its totient is φ = 644051520000.

The previous prime is 691221585937. The next prime is 691221586007. The reversal of 691221585949 is 949585122196.

It is a cyclic number.

It is not a de Polignac number, because 691221585949 - 2²³ = 691213197341 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (61).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (791221585949) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21310554 + ... + 21342964.

It is an arithmetic number, because the mean of its divisors is an integer number (46224535860).

Almost surely, 2^691221585949 is an apocalyptic number.

It is an amenable number.

691221585949 is a deficient number, since it is larger than the sum of its proper divisors (48370987811).

691221585949 is a wasteful number, since it uses less digits than its factorization.

691221585949 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50892.

The product of its digits is 13996800, while the sum is 61.

The spelling of 691221585949 in words is "six hundred ninety-one billion, two hundred twenty-one million, five hundred eighty-five thousand, nine hundred forty-nine".