21447770400 has 324 divisors, whose sum is σ = 87979435362. Its totient is φ = 4902266880.

The previous prime is 21447770371. The next prime is 21447770413. The reversal of 21447770400 is 407774412.

It can be written as a sum of positive squares in 3 ways, for example, as 17860718736 + 3587051664 = 133644^2 + 59892^2 .

It is a super-2 number, since 2×21447770400² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 53 ways as a sum of consecutive naturals, for example, 322404 + ... + 383196.

Almost surely, 2^21447770400 is an apocalyptic number.

21447770400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21447770400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43989717681).

21447770400 is an abundant number, since it is smaller than the sum of its proper divisors (66531664962).

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

21447770400 is a wasteful number, since it uses less digits than its factorization.

21447770400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60833 (or 60810 counting only the distinct ones).

The product of its (nonzero) digits is 43904, while the sum is 36.

The spelling of 21447770400 in words is "twenty-one billion, four hundred forty-seven million, seven hundred seventy thousand, four hundred".