1621778634 has 24 divisors (see below), whose sum is σ = 4015833120. Its totient is φ = 463365288.

The previous prime is 1621778621. The next prime is 1621778659. The reversal of 1621778634 is 4368771261.

1621778634 is a `hidden beast` number, since 1 + 6 + 2 + 1 + 7 + 7 + 8 + 634 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 1621778634.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6435504 + ... + 6435755.

It is an arithmetic number, because the mean of its divisors is an integer number (167326380).

Almost surely, 2^1621778634 is an apocalyptic number.

1621778634 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

1621778634 is an abundant number, since it is smaller than the sum of its proper divisors (2394054486).

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

1621778634 is a wasteful number, since it uses less digits than its factorization.

1621778634 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12871274 (or 12871271 counting only the distinct ones).

The product of its digits is 338688, while the sum is 45.

The square root of 1621778634 is about 40271.3127921105. The cubic root of 1621778634 is about 1174.8899571609.

The spelling of 1621778634 in words is "one billion, six hundred twenty-one million, seven hundred seventy-eight thousand, six hundred thirty-four".