21481770 has 64 divisors (see below), whose sum is σ = 54411264. Its totient is φ = 5417280.

The previous prime is 21481769. The next prime is 21481771. The reversal of 21481770 is 7718412.

It is an interprime number because it is at equal distance from previous prime (21481769) and next prime (21481771).

It is a super-2 number, since 2×21481770² = 922932884665800, which contains 22 as substring.

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 (21481771) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 112375 + ... + 112565.

It is an arithmetic number, because the mean of its divisors is an integer number (850176).

Almost surely, 2^21481770 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21481770, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27205632).

21481770 is an abundant number, since it is smaller than the sum of its proper divisors (32929494).

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

21481770 is a wasteful number, since it uses less digits than its factorization.

21481770 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 387.

The product of its (nonzero) digits is 3136, while the sum is 30.

The square root of 21481770 is about 4634.8430394135. The cubic root of 21481770 is about 277.9862750500.

The spelling of 21481770 in words is "twenty-one million, four hundred eighty-one thousand, seven hundred seventy".