21402020 has 24 divisors (see below), whose sum is σ = 45045504. Its totient is φ = 8541536.

The previous prime is 21402019. The next prime is 21402023. The reversal of 21402020 is 2020412.

It is a junction number, because it is equal to n+sod(n) for n = 21401992 and 21402010.

It is not an unprimeable number, because it can be changed into a prime (21402023) 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, 10829 + ... + 12651.

It is an arithmetic number, because the mean of its divisors is an integer number (1876896).

Almost surely, 2^21402020 is an apocalyptic number.

21402020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21402020 is an abundant number, since it is smaller than the sum of its proper divisors (23643484).

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

21402020 is a wasteful number, since it uses less digits than its factorization.

21402020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2419 (or 2417 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 11.

The square root of 21402020 is about 4626.2317278753. The cubic root of 21402020 is about 277.6418450763.

Adding to 21402020 its reverse (2020412), we get a palindrome (23422432).

The spelling of 21402020 in words is "twenty-one million, four hundred two thousand, twenty".