1621770638 has 32 divisors (see below), whose sum is σ = 2532254400. Its totient is φ = 778542336.

The previous prime is 1621770629. The next prime is 1621770649. The reversal of 1621770638 is 8360771261.

It is a junction number, because it is equal to n+sod(n) for n = 1621770595 and 1621770604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 970868 + ... + 972536.

It is an arithmetic number, because the mean of its divisors is an integer number (79132950).

Almost surely, 2^1621770638 is an apocalyptic number.

1621770638 is a deficient number, since it is larger than the sum of its proper divisors (910483762).

1621770638 is a wasteful number, since it uses less digits than its factorization.

1621770638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1916.

The product of its (nonzero) digits is 84672, while the sum is 41.

The square root of 1621770638 is about 40271.2135153636. The cubic root of 1621770638 is about 1174.8880262694. Note that the first 3 decimals are identical.

The spelling of 1621770638 in words is "one billion, six hundred twenty-one million, seven hundred seventy thousand, six hundred thirty-eight".