21402356 has 12 divisors (see below), whose sum is σ = 37487940. Its totient is φ = 10691520.

The previous prime is 21402331. The next prime is 21402373. The reversal of 21402356 is 65320412.

It can be written as a sum of positive squares in 2 ways, for example, as 9610000 + 11792356 = 3100^2 + 3434^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5330 + ... + 8438.

It is an arithmetic number, because the mean of its divisors is an integer number (3123995).

Almost surely, 2^21402356 is an apocalyptic number.

It is an amenable number.

21402356 is a deficient number, since it is larger than the sum of its proper divisors (16085584).

21402356 is a wasteful number, since it uses less digits than its factorization.

21402356 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4834 (or 4832 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 21402356 is about 4626.2680423858. The cubic root of 21402356 is about 277.6432980104.

Adding to 21402356 its reverse (65320412), we get a palindrome (86722768).

The spelling of 21402356 in words is "twenty-one million, four hundred two thousand, three hundred fifty-six".