21436780 has 24 divisors (see below), whose sum is σ = 45310608. Its totient is φ = 8518848.

The previous prime is 21436763. The next prime is 21436781. The reversal of 21436780 is 8763412.

It is not an unprimeable number, because it can be changed into a prime (21436781) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 274 + ... + 6553.

It is an arithmetic number, because the mean of its divisors is an integer number (1887942).

It is a vampire number, since it can be written as 3140 ⋅ 6827 (with its own digits).

Almost surely, 2^21436780 is an apocalyptic number.

21436780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21436780 is an abundant number, since it is smaller than the sum of its proper divisors (23873828).

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

21436780 is a wasteful number, since it uses less digits than its factorization.

21436780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6993 (or 6991 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 31.

The square root of 21436780 is about 4629.9870410186. The cubic root of 21436780 is about 277.7920740494.

The spelling of 21436780 in words is "twenty-one million, four hundred thirty-six thousand, seven hundred eighty".