21431402 has 4 divisors (see below), whose sum is σ = 32147106. Its totient is φ = 10715700.

The previous prime is 21431401. The next prime is 21431489. The reversal of 21431402 is 20413412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 11703241 + 9728161 = 3421^2 + 3119^2 .

It is not an unprimeable number, because it can be changed into a prime (21431401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5357849 + ... + 5357852.

Almost surely, 2^21431402 is an apocalyptic number.

21431402 is a deficient number, since it is larger than the sum of its proper divisors (10715704).

21431402 is a wasteful number, since it uses less digits than its factorization.

21431402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10715703.

The product of its (nonzero) digits is 192, while the sum is 17.

The square root of 21431402 is about 4629.4062254246. The cubic root of 21431402 is about 277.7688415377.

Adding to 21431402 its reverse (20413412), we get a palindrome (41844814).

The spelling of 21431402 in words is "twenty-one million, four hundred thirty-one thousand, four hundred two".