21512431402 has 32 divisors (see below), whose sum is σ = 40292095104. Its totient is φ = 8368747200.

The previous prime is 21512431309. The next prime is 21512431403. The reversal of 21512431402 is 20413421512.

It is not an unprimeable number, because it can be changed into a prime (21512431403) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3873 + ... + 207460.

It is an arithmetic number, because the mean of its divisors is an integer number (1259127972).

Almost surely, 2^21512431402 is an apocalyptic number.

21512431402 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21512431402 is a deficient number, since it is larger than the sum of its proper divisors (18779663702).

21512431402 is a wasteful number, since it uses less digits than its factorization.

21512431402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 212014.

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

Adding to 21512431402 its reverse (20413421512), we get a palindrome (41925852914).

The spelling of 21512431402 in words is "twenty-one billion, five hundred twelve million, four hundred thirty-one thousand, four hundred two".