1621055566 has 32 divisors (see below), whose sum is σ = 2759531040. Its totient is φ = 708009984.

The previous prime is 1621055563. The next prime is 1621055567. The reversal of 1621055566 is 6655501261.

It is a super-2 number, since 2×1621055566² = 5255642296119160712, which contains 22 as substring.

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621055563) 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, 766126 + ... + 768238.

It is an arithmetic number, because the mean of its divisors is an integer number (86235345).

Almost surely, 2^1621055566 is an apocalyptic number.

1621055566 is a deficient number, since it is larger than the sum of its proper divisors (1138475474).

1621055566 is a wasteful number, since it uses less digits than its factorization.

1621055566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3700.

The product of its (nonzero) digits is 54000, while the sum is 37.

The square root of 1621055566 is about 40262.3343337169. The cubic root of 1621055566 is about 1174.7153234597.

The spelling of 1621055566 in words is "one billion, six hundred twenty-one million, fifty-five thousand, five hundred sixty-six".