21129370 has 8 divisors (see below), whose sum is σ = 38032884. Its totient is φ = 8451744.

The previous prime is 21129359. The next prime is 21129377. The reversal of 21129370 is 7392112.

It can be written as a sum of positive squares in 2 ways, for example, as 19686969 + 1442401 = 4437^2 + 1201^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21129377) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1056459 + ... + 1056478.

Almost surely, 2^21129370 is an apocalyptic number.

21129370 is a deficient number, since it is larger than the sum of its proper divisors (16903514).

21129370 is a wasteful number, since it uses less digits than its factorization.

21129370 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2112944.

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 21129370 is about 4596.6694464579. The cubic root of 21129370 is about 276.4578011022.

The spelling of 21129370 in words is "twenty-one million, one hundred twenty-nine thousand, three hundred seventy".