21375570 has 32 divisors (see below), whose sum is σ = 54002880. Its totient is φ = 5400000.

The previous prime is 21375569. The next prime is 21375577. The reversal of 21375570 is 7557312.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (21375577) 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, 18181 + ... + 19320.

It is an arithmetic number, because the mean of its divisors is an integer number (1687590).

Almost surely, 2^21375570 is an apocalyptic number.

21375570 is an abundant number, since it is smaller than the sum of its proper divisors (32627310).

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

21375570 is a wasteful number, since it uses less digits than its factorization.

21375570 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37530.

The product of its (nonzero) digits is 7350, while the sum is 30.

The square root of 21375570 is about 4623.3721459558. The cubic root of 21375570 is about 277.5274220121.

It can be divided in two parts, 21375 and 570, that added together give a triangular number (21945 = T₂₀₉).

The spelling of 21375570 in words is "twenty-one million, three hundred seventy-five thousand, five hundred seventy".