21601554 has 32 divisors (see below), whose sum is σ = 48553344. Its totient is φ = 6357120.

The previous prime is 21601519. The next prime is 21601561. The reversal of 21601554 is 45510612.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4227 + ... + 7814.

It is an arithmetic number, because the mean of its divisors is an integer number (1517292).

Almost surely, 2^21601554 is an apocalyptic number.

21601554 is an abundant number, since it is smaller than the sum of its proper divisors (26951790).

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

21601554 is a wasteful number, since it uses less digits than its factorization.

21601554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12082.

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 21601554 is about 4647.7471962231. The cubic root of 21601554 is about 278.5020085872.

It can be divided in two parts, 21601 and 554, that added together give a triangular number (22155 = T₂₁₀).

The spelling of 21601554 in words is "twenty-one million, six hundred one thousand, five hundred fifty-four".