21435820 has 24 divisors (see below), whose sum is σ = 51446304. Its totient is φ = 7349376.

The previous prime is 21435769. The next prime is 21435833. The reversal of 21435820 is 2853412.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 76417 + ... + 76696.

It is an arithmetic number, because the mean of its divisors is an integer number (2143596).

Almost surely, 2^21435820 is an apocalyptic number.

21435820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21435820 is an abundant number, since it is smaller than the sum of its proper divisors (30010484).

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

21435820 is a wasteful number, since it uses less digits than its factorization.

21435820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153129 (or 153127 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 25.

The square root of 21435820 is about 4629.8833678614. The cubic root of 21435820 is about 277.7879272143.

The spelling of 21435820 in words is "twenty-one million, four hundred thirty-five thousand, eight hundred twenty".