21649402 has 8 divisors (see below), whose sum is σ = 32692500. Its totient is φ = 10751904.

The previous prime is 21649361. The next prime is 21649429. The reversal of 21649402 is 20494612.

It can be written as a sum of positive squares in 2 ways, for example, as 19280881 + 2368521 = 4391^2 + 1539^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36027 + ... + 36622.

Almost surely, 2^21649402 is an apocalyptic number.

21649402 is a deficient number, since it is larger than the sum of its proper divisors (11043098).

21649402 is a wasteful number, since it uses less digits than its factorization.

21649402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72800.

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 21649402 is about 4652.8917889846. The cubic root of 21649402 is about 278.7074866626.

The spelling of 21649402 in words is "twenty-one million, six hundred forty-nine thousand, four hundred two".