21400770 has 64 divisors (see below), whose sum is σ = 53415936. Its totient is φ = 5483520.

The previous prime is 21400751. The next prime is 21400781. The reversal of 21400770 is 7700412.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 156142 + ... + 156278.

It is an arithmetic number, because the mean of its divisors is an integer number (834624).

Almost surely, 2^21400770 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21400770, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26707968).

21400770 is an abundant number, since it is smaller than the sum of its proper divisors (32015166).

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

21400770 is a wasteful number, since it uses less digits than its factorization.

21400770 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 315.

The product of its (nonzero) digits is 392, while the sum is 21.

The square root of 21400770 is about 4626.0966267470. The cubic root of 21400770 is about 277.6364396821.

The spelling of 21400770 in words is "twenty-one million, four hundred thousand, seven hundred seventy".