21002154434 has 4 divisors (see below), whose sum is σ = 31503231654. Its totient is φ = 10501077216.

The previous prime is 21002154367. The next prime is 21002154451. The reversal of 21002154434 is 43445120012.

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., 13311390625 + 7690763809 = 115375^2 + 87697^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5250538607 + ... + 5250538610.

Almost surely, 2^21002154434 is an apocalyptic number.

21002154434 is a deficient number, since it is larger than the sum of its proper divisors (10501077220).

21002154434 is a wasteful number, since it uses less digits than its factorization.

21002154434 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10501077219.

The product of its (nonzero) digits is 3840, while the sum is 26.

Adding to 21002154434 its reverse (43445120012), we get a palindrome (64447274446).

The spelling of 21002154434 in words is "twenty-one billion, two million, one hundred fifty-four thousand, four hundred thirty-four".