21012154 has 4 divisors (see below), whose sum is σ = 31518234. Its totient is φ = 10506076.

The previous prime is 21012151. The next prime is 21012161. The reversal of 21012154 is 45121012.

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., 17032129 + 3980025 = 4127^2 + 1995^2 .

It is not an unprimeable number, because it can be changed into a prime (21012151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5253037 + ... + 5253040.

Almost surely, 2^21012154 is an apocalyptic number.

21012154 is a deficient number, since it is larger than the sum of its proper divisors (10506080).

21012154 is a wasteful number, since it uses less digits than its factorization.

21012154 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10506079.

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 21012154 is about 4583.9016132548. The cubic root of 21012154 is about 275.9456327135.

Adding to 21012154 its reverse (45121012), we get a palindrome (66133166).

The spelling of 21012154 in words is "twenty-one million, twelve thousand, one hundred fifty-four".