1621981634 has 48 divisors (see below), whose sum is σ = 3070477368. Its totient is φ = 636910848.

The previous prime is 1621981591. The next prime is 1621981639. The reversal of 1621981634 is 4361891261.

It can be written as a sum of positive squares in 4 ways, for example, as 792253609 + 829728025 = 28147^2 + 28805^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1621981591 and 1621981600.

It is not an unprimeable number, because it can be changed into a prime (1621981639) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 169892 + ... + 179184.

Almost surely, 2^1621981634 is an apocalyptic number.

1621981634 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

1621981634 is a deficient number, since it is larger than the sum of its proper divisors (1448495734).

1621981634 is a wasteful number, since it uses less digits than its factorization.

1621981634 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9459 (or 9452 counting only the distinct ones).

The product of its digits is 62208, while the sum is 41.

The square root of 1621981634 is about 40273.8331177950. The cubic root of 1621981634 is about 1174.9389759163.

The spelling of 1621981634 in words is "one billion, six hundred twenty-one million, nine hundred eighty-one thousand, six hundred thirty-four".