20945556 has 18 divisors (see below), whose sum is σ = 52945802. Its totient is φ = 6981840.

The previous prime is 20945537. The next prime is 20945563. The reversal of 20945556 is 65554902.

It can be written as a sum of positive squares in only one way, i.e., 20250000 + 695556 = 4500^2 + 834^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a super-2 number, since 2×20945556² = 877432632298272, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 581821 = 20945556 / (2 + 0 + 9 + 4 + 5 + 5 + 5 + 6).

It is a self number, because there is not a number n which added to its sum of digits gives 20945556.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 290875 + ... + 290946.

Almost surely, 2^20945556 is an apocalyptic number.

It is an amenable number.

20945556 is an abundant number, since it is smaller than the sum of its proper divisors (32000246).

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

20945556 is a wasteful number, since it uses less digits than its factorization.

20945556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 581831 (or 581826 counting only the distinct ones).

The product of its (nonzero) digits is 54000, while the sum is 36.

The square root of 20945556 is about 4576.6315123680. The cubic root of 20945556 is about 275.6537876977.

The spelling of 20945556 in words is "twenty million, nine hundred forty-five thousand, five hundred fifty-six".