691821402 has 32 divisors (see below), whose sum is σ = 1413972288. Its totient is φ = 225578496.

The previous prime is 691821401. The next prime is 691821437. The reversal of 691821402 is 204128196.

It is not an unprimeable number, because it can be changed into a prime (691821401) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 109173 + ... + 115335.

It is an arithmetic number, because the mean of its divisors is an integer number (44186634).

Almost surely, 2^691821402 is an apocalyptic number.

691821402 is an abundant number, since it is smaller than the sum of its proper divisors (722150886).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

691821402 is a wasteful number, since it uses less digits than its factorization.

691821402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6574.

The product of its (nonzero) digits is 6912, while the sum is 33.

The square root of 691821402 is about 26302.4980182491. The cubic root of 691821402 is about 884.4324414854.

Adding to 691821402 its reverse (204128196), we get a palindrome (895949598).

The spelling of 691821402 in words is "six hundred ninety-one million, eight hundred twenty-one thousand, four hundred two".